Tory leadership contender Matt Hancock has drawn Labour scorn after he appeared to brand Jeremy Corbyn anti-Semitic.
The Health Secretary used a private hustings with Tory MPs to attack the Labour leader.
According to a supporter of Mr Hancock, the Cabinet minister told colleagues at the gathering: “The Conservative Party has to get this right. If we don’t, we could end up with the first anti-Semitic leader of a Western nation since the Second World War.”
In response, shadow chancellor John McDonnell told the Press Association the comments were “a disgrace”.
A Labour source told the Press Association: “This baseless political attack rings hollow from a minister in a party that has supported Governments that actively promote anti-Semitic policies in Hungary and Poland and has spent the week wooing Trump – the man who refused to condemn neo-fascists in Charlottesville who chanted ‘Jews will not replace us’.
“Numerous candidates in the Conservative leadership contest have been accused of racism, Islamophobia, homophobia and misogyny, one of whom may be the next prime minister.”
The remarks came as the battle for Downing Street turned increasingly heated.
Ex-Brexit secretary Dominic Raab said he would be prepared to temporarily shut down Parliament to make sure EU withdrawal happens on October 31.
An MP who is supporting Mr Raab said: “Dominic made clear that he would use every lever of the executive to ensure that the UK can leave the EU at the end of October.
“He also made clear that anyone who rules out any options, or signals that they would take no-deal off the table and that they would allow further extensions, is just weakening our negotiating leverage in Brussels.”
Work and Pensions Secretary Amber Rudd said: “I think it’s outrageous to consider proroguing Parliament. We are not Stuart kings.”
Foreign Secretary Jeremy Hunt told the hustings that Parliament would block a no-deal Brexit so the Tories needed a leader who could negotiate a better agreement.
Environment Secretary Michael Gove insisted he was open to a delayed Brexit to achieve a deal.
Speaking at an event in Westminster organised by The Spectator, Mr Gove said Brexit could be delayed for a few weeks to get a deal.
He said: “The critical thing to do is to recognise that if we’re not 100% out by midnight on October 31 then we risk making that arbitrary deadline the determinant of what a good deal is.
“And I think if we’re so close to the wire with what is, I believe, a better deal, then it would be right to take those extra few days or weeks in order to land it and to make sure that we’re out.”
Meanwhile, European Research Group (ERG) deputy chairman Steve Baker has announced he could stand in the Tory leadership contest to deliver a no-deal Brexit.
Launching a paper on how to rip up the current Brexit deal and achieve a “clean, managed” exit from the EU, Mr Baker said the new leader must be willing to follow its recommendations.
Otherwise, Mr Baker said, the group would need to put forward its own candidate – and he was willing to join the race when it officially opens on Monday.
Mr Baker’s potential candidacy would take the number of contenders in the leadership race back up to 12 if he does decide to stand on Monday.