Asked if she was too closely associated with Boris Johnson, Truss said she was a “loyal person” and that was why she did not resign when other cabinet colleagues did.

She said she spoke up privately against the planned rise in national insurance and said: “The change we need to deliver is change on the economy.” She promised that she would “review the taxation of families to ensure that people aren’t penalised for taking time out to care for children or elderly relatives”.

The six hopefuls in the Tory leadership race will be whittled down further at 3pm. MPs are voting again today, with the candidate with the least votes eliminated. Penny Mordaunt came second behind Rishi Sunak in the first ballot yesterday, with 67 votes to his 88. Suella Braverman won 32 and Tom Tugendhat 37. The threshold was 30.

Sunak, who looks likely to make the final two candidates put to Conservative members over the summer, said this morning that he believed in “hard work and aspiration”. He told Today on Radio 4: “If I’m prime minister then I’ll be making the case for that with vigour.”

This morning Lord Frost, the former Brexit minister, launched a stinging attack on Mordaunt, his former deputy in the EU negotiations. He said that he had “grave reservations” about her becoming a frontrunner to lead the Conservative Party, and questioned whether she would be able to “take tough decisions”.

Penny Mordaunt’s leadership rivals have refused to publicly be drawn into attacking her after a scathing broadside by the former Brexit minister Lord Frost.

Scrutiny of Mordaunt stepped up today after she came in second to Rishi Sunak in the first round of balloting yesterday.

However, Liz Truss, the foreign secretary, said today she would not be making “any disparaging comments” about any of the hopefuls when asked if she was concerned about Mordaunt’s success.

“I think, in fact, the Conservative race shows what a broad range of talent we have in the Conservative Party,” she said. “I’m putting forward a positive agenda.”

That has not stopped Truss’s backers attacking her rivals. After Frost told TalkTV this morning that Mordaunt was too inexperienced to be prime minister, Simon Clarke, the Treasury chief secretary who is supporting Truss, retweeted a video of the clip.

Tom Tugendhat, at a press conference this morning, said his fellow candidates needed to be prepared for criticism.

He said: “It’s not always easy but I think it’s fair because if you are running for an office like this it is fair that those who know you express views. Some of them are going to be nice, some of them less so. This is a really short interview round for a hell of a big job.”

Candidates have publicly tried to keep their campaigns clean. Suella Braverman and Kemi Badenoch were photographed last night with their arms around each other in Westminster.

Privately briefings have become increasingly bitter, leading Jeremy Hunt, who along with Nadhim Zahawi, the chancellor, dropped out of the race yesterday, to warn: “Smears and attacks may bring short-term tactical gain but always backfire long term.”

Sunak defended the involvement of Sir Gavin Williamson, the former chief whip and education secretary, in his campaign after accusations of “dirty tricks”. He insisted on Today on Radio 4 that it was Mel Stride, the Treasury committee chairman, running his campaign, not Williamson.

On Williamson’s role, Sunak said: “Like all the members of parliament who are on my team, they are talking to colleagues and making the case for my candidacy because they believe that I am the best person to beat Keir Starmer and the Labour Party and I’m really grateful for all their support.”

Tom Tugendhat has vowed to keep fighting in the Tory leadership contest as he said that running made him feel like a “prom queen”.

The chairman of the foreign affairs committee is languishing in the leadership race behind the frontrunners Penny Mordaunt, Rishi Sunak and Liz Truss.

He secured the support of 37 Tory MPs yesterday to make it to the second round of the contest and is hoping to avoid a last-placed finish later today, which would allow him to progress to the TV debates starting on Friday.

Tugendhat held a question-and-answer session with journalists this morning. “I don’t quit,” he said. “A lot of people are looking at their options today and thinking differently.”

Tugendhat, who has no ministerial experience, also defended the right of Lord Frost and Simon Clarke to attack Mordaunt’s record in government, after the pair criticised her lack of diligence as a minister.

“If you are running for an office like this it is fair that those who know you express views. Some of them are going to be nice and some of them aren’t,” he said.

Asked how he felt about the contest, he said: “I feel like a prom queen.”

Tugendhat also reaffirmed his commitment to the government’s target of hitting net zero emissions by 2050.

The senior member of the One Nation Group of Tory MPs surprised many when he appeared to argue for delaying the target date at a hustings last night in a move interpreted by some as an attempt to appeal to the right of the Conservative party.

Tugendhat, 49, denied he was “showing some leg” to climate change sceptics in the party. “I’ve got a lot of leg to flash but when you get to my age nobody wants to see it,” he said.

Penny Mordaunt’s stance on trans rights may be her biggest barrier in winning colleagues’ votes in today’s second ballot as further scrutiny was applied to her past comments (Geraldine Scott writes).

Last night she was taken to task over her beliefs at the 1922 Committee hustings, while other MPs want her to move on and stop talking about the divisive issue.

Mordaunt has previously said she believes trans women are women but early in her campaign she posted a late-night Twitter thread trying to set the record straight after being accused of being a “woke” candidate.

Mordaunt was asked “by an older MP about being woke” during hustings held by the 92 Group of right-wing grandees.

Julian Knight, who is backing Liz Truss, the foreign secretary, said Mordaunt repeated a joke from her launch event, based on Margaret Thatcher’s declaration that “every prime minister needs a Willie [Whitelaw, her deputy prime minister]”.

Knight said that that had made him “cringe” and added: “I’m not certain I’ve got a satisfactory answer to that question.”

At the 1922 Committee hustings Mordaunt was asked about a bill in which she was involved in which the word “women” was replaced with “pregnant people”.

Sky News reported that Mordaunt, who was paymaster-general at the time, told the hustings that she “only had a day to read the bill”, which was said to have left the MP Sir John Hayes “incandescent”. Hayes had attempted to amend the bill to reinstate the words mother and woman, and this was later achieved in the House of Lords.

Suella Braverman, the attorney-general and a competitor in the leadership contest, was able to take maternity leave under the bill. She said the wrangling over language made her pregnancy “needlessly” stressful, and while she did not name Mordaunt it was interpreted as an attack on her involvement.

Another MP in the room said that Mordaunt was now focusing too much on the issue and was starting to sound like a “broken record”.

Identity politics has become a key talking point and Mordaunt has said she has always “stood up for women”.

Lord Frost, the former Brexit minister, told TalkTV this morning: “She, I think, has been very clearly on one side of this argument and now she’s trying to give the impression that actually it wasn’t quite like that.”

One red wall MP told The Times that the issue was the main reason they had backed Kemi Badenoch for leader, who has pushed to abolish gender-neutral lavatories. “It plays very well with my voters,” they said.

Asked if constituents cared about the matter, after a poll by Opinium of 500 Tory members put trans issues as 26th and 27th on a list of priorities, the MP said: “They will at the next election.”

Liz Truss has formally launched her pitch to lead the Conservative Party, saying she is “ready to be prime minister from day one” (Oliver Wright and Geraldine Scott write).

Truss, the foreign secretary, drew on her upbringing in Leeds as she laid out her priorities to supporters this morning, and pledged to “make Britain a high-growth economy over the next ten years” and put the economy on an “upward trajectory by 2024.

Promising to cut taxes, tackle the cost of energy and control government spending, she said: “We need to be honest with the public, this will be tough, it will take time, but I am determined to deliver.”

Truss pledged to create “new low-tax regulation zones” to attract investment, and review tax for families so that “people aren’t penalised for taking time out to care for children or elderly relatives”.

The foreign secretary, who came third in yesterday’s ballot with 50 votes, talked up her cabinet credentials, saying: “I don’t give in to Whitehall, I don’t give in to vested interests, and I don’t give in to naysayers.”

However, she admitted “our economy will not get back on track overnight”. She said: “Times are going to be tough, but I know that I can get us on an upward trajectory by 2024. We can get there by delivering our promises, ensuring spades are in the ground.”

Asked if she was too closely associated with Boris Johnson, Truss said she was a “loyal person” and that was why she did not resign when other cabinet colleagues did.

She said she spoke up privately against the planned rise in national insurance and said: “The change we need to deliver is change on the economy.”

She promised that she would “review the taxation of families to ensure that people aren’t penalised for taking time out to care for children or elderly relatives”, and to “turbocharge the rural economy” by cutting “pointless regulation” that “gets in the way” of farmers and food producers.

Truss has won the support of two rising stars ot the party as she attempts to generate momentum.

James Heappey, a defence minister and close ally of Ben Wallace, the defence secretary, said: “I have sat in meetings with Liz you won’t be able to read about for 30 years. This is a serious time and we need a serious prime minister. The fact she’s backing 3% [of GDP on defence spending] means it’s a slam dunk for me.”

Ed Argar, a former health minister, said: “Liz has the breadth of experience across government. She’s serious and has a clear plan. She’s the right person.”

The first ballot of the Conservative leadership contest keeps the race wide open with only a small number of new votes up for grabs (Henry Zeffman, George Grylls and Geraldine Scott write).

Between them Nadhim Zahawi and Jeremy Hunt were backed in the first ballot by only 43 MPs, 12 per cent of the voters available.

Yet in such a tight race, with just 18 votes separating Suella Braverman in sixth and Liz Truss in third, how Zahawi and Hunt supporters vote today could prove pivotal.

Hunt’s 14 known backers are a little more ideologically coherent than Zahawi’s 14. Many of them are established Conservatives — only one was elected in 2019 and a majority were in parliament before 2010.

Much of this old-school grouping is likely to follow Hunt’s lead towards Rishi Sunak. But perhaps not all of them; Esther McVey, who Hunt proposed to make deputy prime minister, and her husband Philip Davies might move more naturally to Liz Truss or Kemi Badenoch.

Zahawi’s support base, described by a senior MP as “personal not ideological”, is harder to judge. Six of them are from the 2019 intake and will be trying to work out who is best placed to hold onto the red wall.

What would probably most boost candidates on the right, Truss in particular, would be if Braverman, the lowest-ranked candidate left in the contest, decided to withdraw. Her 15 known backers are typically Brexiteers. Braverman’s team were adamant last night that she would not concede. But most are expected to back Truss if she is eliminated today.

Badenoch may struggle to attract new Brexiteer MPs because some are suspicious of Michael Gove, her most eyecatching supporter. Steve Baker, Braverman’s campaign manager, has accused Gove, and thereby Badenoch, of acting as a stalking horse for the Sunak campaign.

But others believe that Badenoch’s first-round performance was so strong that other campaigns will see her as a surging force.

Then there are the frontrunners. Sunak’s victory was ostensibly commanding, but some MPs were surprised he was not leading by more. The momentum, unquestionably, is with Penny Mordaunt.

The YouGov poll yesterday afternoon which showed her not just beating but eviscerating every other contender among Conservative members has transformed the narrative of this election.

Her rivals’ best hope may be to keep Mordaunt from the final two. But it would require significant volatility in MPs’ movements to make that a reality.

Rishi Sunak has denied being “too rich and too slick” to be prime minister and said he does not “judge people by their bank accounts” (Geraldine Scott writes).

The former chancellor said he hoped his colleagues and Conservative members would judge him by his actions, claiming: “Whenever I’ve needed to step in to support people, I have.”

Sunak is believed to be the richest serving MP, and he became the first frontline politician to be ranked on the Sunday Times Rich List this year alongside his wife, Akshata Murty, because of their £730 million fortune.

Asked on Radio 4’s Today whether that meant he could not appreciate the cost of living crisis faced by Britons he said: “Beyond character you can judge me by my actions.

“Over the last couple of years I don’t think anyone can doubt that I’ve done an enormous amount to support people, families and the economy through a very difficult time.”

He said he would “of course” like to stay in the UK even if he loses the leadership contest. He previously held a green card, giving him permanent residence in the US, for six years while an MP.

Sunak gained the support of Jeremy Hunt yesterday after the former health secretary was knocked out of the leadership contest to be the next Tory leader.

Supporters of Tom Tugendhat are understood to have expected Hunt to back their camp, and are frustrated that he did not do so. However, that does not guarantee that Hunt’s 18 votes will not go to Tugendhat in the second round of voting today.

He could also pick up votes from Nadhim Zahawi’s caucus. A member of the chancellor’s team said of Zahawi’s 25 votes: “We were recruiting from the centre and right of centre. Don’t be surprised if Tom gets a bump.”

Penny Mordaunt “wasn’t always visible” and was moved on from working on Brexit negotiations, it has been claimed.

Lord Frost, the former Brexit minister, said this morning that he had “grave reservations” about her becoming a frontrunner to lead the Conservative Party, and questioned whether she would be able to “take tough decisions”.

Writing in the Daily Mail this morning, Mordaunt promised to make defence the “first duty” of government. But Frost, who said that Mordaunt was “notionally” his deputy during Brexit negotiations last year, claimed she “did not master the detail”.

He told TalkTV: “She wouldn’t always deliver tough messages to the European Union when that was necessary and I’m afraid she wasn’t sort of fully accountable, she wasn’t always visible, and I’m afraid sometimes I didn’t even know where she was, and I’m afraid this became such a problem that after six months I had to ask the prime minister to move her on and find somebody else to support me.”

Frost has not yet revealed who he is backing to be prime minister, but said he felt the country was “rushing” to reach net zero too quickly and the new leader had to “stand up” for themselves over culture wars issues.

“I have worked with Penny, to be honest I’m quite surprised that she is where she is in this leadership race,” he said. “She was my deputy, notionally rather than really, I think, in the Brexit talks last year.”

Asked about the term notionally, he replied: “So, I mean, I’m sorry to say this, that I felt she did not master the detail that was necessary in the negotiations last year, she wouldn’t always deliver tough messages to the European Union when that was necessary.

“And I’m afraid she wasn’t fully accountable, she wasn’t always visible, sometimes I didn’t even know where she was, and I’m afraid that this became such a problem that after six months I had to ask the prime minister to move her on and find somebody else,to support me.

“You have to remember this was a time when we were in a major confrontation over Northern Ireland and it was extremely difficult . . . We just were not getting the support we needed.”

Asked whether in his view, as his junior, she was not up to the job at a low level, and therefore wouldn’t be up to the job as prime minister, he replied: “That was my view; I’m afraid if you are prime minister you’ve got to take responsibility, you’ve got to able to run the machine, you’ve got to able to take tough decisions, deliver tough messages. Anybody can be photographed in a video with I Vow To Thee My Country, but it is what you do in practice. Are you able to be tough, are you able to lead, are you able to take responsibility? I’m talking only about my own experience with her, but from the basis of what I saw I’m afraid that I would have great reservations about that.”

Asked whether Brexit would be safe in her hands, he said: “If Brexit is going to be safe, it’s going to need a few things, but one of them is the need is the ability to be tough, to be clear, to deliver tough messages, to stand up for the decisions that we have taken as a country and make a success of them. And not be pushed back into some sort of closer relationship.

“I would worry on the basis of what I have seen that we wouldn’t necessarily get that from Penny.”