LONDON — 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.

But Ms Mordaunt's supporters insisted she was ready to become PM.

Ex-Chancellor Rishi Sunak came first in Thursday's second round of voting, with Ms Mordaunt second and Ms Truss third.

The eliminated candidate, Attorney-General Suella Braverman, gave 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 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."

And, speaking to BBC Radio 4's Today programme, he said Ms Truss's record in office demonstrated "her character and her grit".

But supporters of Ms Mordaunt rejected the criticisms of their candidate, with senior Tory MP Dame Maria Miller telling Sky News: "I have seen her to be a very effective campaigner.

"She really is one of the leading proponents of Brexit and was throughout the campaign."

And John Lamont, who is coordinating Ms Mordaunt's campaign in Scotland, told Today she was running a positive campaign.

He 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".

Sunak got 101 votes on Thursday, with Ms Mordaunt receiving 83 and Ms Truss 64. Ms Badenoch got 49 votes and 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 19:00 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 Johnson will leave office. — BBC