Backers of Foreign Secretary Liz Truss have attacked Tory leadership rival Penny Mordaunt, as they fight to stay in the race to succeed Boris Johnson.
Former Brexit Minister Lord Frost said Ms Mordaunt did not “master detail” and ex-party leader Sir Iain Duncan Smith questioned her level of experience.
She said rivals were trying to stop her as they did “not want to run against me” in the final vote by Tory members.
Ex-Chancellor Rishi Sunak came first in Thursday’s second round of MPs’ voting.
Ms Mordaunt second and Ms Truss third, while the eliminated candidate, Attorney-General Suella Braverman, has given her backing to Ms Truss.
Writing in the Daily Telegraph, Lord Frost urged former Equalities Minister Kemi Badenoch, who came fourth in Thursday’s vote by MPs, to leave the race and throw her support behind Ms Truss “in return for a serious job” in government.
But Ms Badenoch’s campaign said she had “no intention of stepping down” and was “in it to win”.
The Conservative Home website is holding a hustings event involving all the candidates from 13:00 BST.
With the field now narrowed to five – and ahead of the first of three live TV debates on Friday evening – the comments coming from the rival camps are becoming more bitter and personal.
Lord Frost attacked Ms Mordaunt, who once served under him, telling Talk TV that she “did not master the detail that was necessary” and had been “absent on parade” during Brexit negotiations with the EU.
Sir Iain questioned Trade Minister and former Defence Secretary Ms Mordaunt’s suitability to be prime minister, telling LBC: “We can’t just elect somebody because for a short period of time they may look better than others.
“What we’re actually electing is not, in a way, a popularity contest.”
Speaking about Ms Mordaunt, another Truss supporter, Julian Knight, told BBC 5 live: “We don’t need an accidental prime minister.”
Supporters of several of Ms Mordaunt’s opponents have also criticised her comments on trans rights when she was equalities minister.
Despite the name, Lord Frost has turned up the temperature in the leadership race.
Initially allies of Liz Truss, such as Jacob Rees-Mogg, were gunning for Rishi Sunak, dubbing him the “high-tax chancellor”.
But with Penny Mordaunt beating Ms Truss in to third place in the MPs’ ballots so far, they are now taking aim at the former defence secretary.
Essentially the charge is that she’s too lazy and too “woke”.
But Lord Frost has exposed in public an aspect of leadership contests usually conducted in private. He is offering fourth-placed candidate Kemi Badenoch a deal – “a serious job” – if she drops out and backs Ms Truss.
The Truss team says she herself isn’t offering posts, but you can be assured that when all candidates try to build a coalition of support, they won’t simply be relying on a policy platform to get fellow MPs to rally to their banner.
And the Frost intervention also reveals a cold, hard reality.
It’s not clear at this stage who will make the final run-off.
So you can expect the battle to become more brutal in the coming days.
But Ms Mordaunt dismissed the criticisms of her, telling Sky News she did not “have a profile” with the public because she had “just been getting on with the job” of being a minister prior to the Tory leadership contest prompted by Mr Johnson’s resignation.
Asked about what supporters of her opponents had said, she replied: “People are obviously trying to stop me getting into the final [vote by party members] because they don’t want to run against me…
“Understandably people, having seen my polling and having seen how I would fare against them in the final round of this contest, it’s understandable how they’re trying to stop me.”
Ms Mordaunt added: “Anyone going for this job needs to be tested and scrutinised.”
But she said her campaign was “not engaging in any” sniping.
John Lamont, who is coordinating Ms Mordaunt’s campaign in Scotland, called her an “electoral asset” and compared her to former Tory Prime Minister David Cameron, saying he had also not been well known by the public before becoming party leader.
There had been speculation that backbench MP Tom Tugendhat, who came fifth in Thursday’s vote, might drop out of the contest.
But in a tweet he said he would stay on and put his “vision for Britain forward to the public”.
Mr Sunak got 101 votes on Thursday, with Ms Mordaunt receiving 83 and Ms Truss 64. Ms Badenoch got 49 votes and Mr Tugendhat 32.
Former Brexit minister Steve Baker has backed Ms Truss, and the BBC understands most of the 27 Tory MPs who voted for Ms Braverman in round two are expected to do the same.
Tory MPs will whittle the runners down to two through further votes next week, before a postal ballot of Conservative Party members will decide the winner.
The remaining candidates will take part in debates from 19:00 BST on Friday on Channel 4, 19:00 on Sunday on ITV, and 20:00 on Tuesday on Sky News.
The next round of voting takes place on Monday and the final result will be announced on 5 September, when Mr Johnson will leave office.