Labour leader Sir Keir Starmer said the Tories have "lost the plot" as opposing teams campaigning to make Rishi Sunak and Liz Truss prime minister tore each other apart after their bruising debate last night.
Infighting continued between the two Tory leadership hopefuls this morning, with Ms Truss's team describing her rival's performance as "unfortunate" for the way he spoke over the foreign secretary in the BBC debate.
"That's not the Rishi Sunak I know," said Simon Clarke, a key ally of Ms Truss who worked very closely with Mr Sunak as chief secretary to the Treasury before leadership hopeful resigned as chancellor.
Another supporter, Cabinet colleague Therese Coffey, said Mr Sunak had been "mansplaining" his opponent and Mr Clarke said the former chancellor's debating tactics "would have got people's backs up".
Many commentators said Mr Sunak was aggressive in the debate, much of which focused on tax and spending plans, with some accusing him of behaving in a way which would be damaging to the Tory party long-term.
But senior Tory David Davis backed Mr Sunak's performance, saying both camps should "be able to defend their own position" and his candidate was "passionate" about his position and "calling it mansplaining is frankly patronising".
Both sides disagree on how to manage the economy, with Ms Truss saying she would cut taxes because Mr Sunak's tax rises would cause a recession but he said her approach would lead to soaring mortgage rates.
During the debate Mr Sunak accused his opponent of promising £40 billion in unfunded tax cuts, which includes her pledge to reverse the National Insurance rise, but Ms Truss said she didn't believe his "negative declinist language".
"This is scaremongering," she said, "this is Project Fear," but Mr Sunak turned the attack around, reminding Ms Truss of her support for Remain in the 2016 EU referendum.
"I remember who was on the side of Project Fear in the referendum and it wasn’t me," he said.
The two leadership hopefuls will go head-to-head again this evening, with more damaging attacks likely to be delivered during TalkTV's debate at 6pm.
Starmer says the Tories have lost the plot
As the two former Cabinet colleagues battle it out to lead the Conservatives, Labour says the whole contest has demonstrated the party to have "lost any real sense of purpose".
Sir Keir, speaking to the BBC about the debate, said: "I watched as much as I could bear of it, because it showed just the two contenders taking lumps out of each other, talking over each other, talking about clothing and earrings instead of the health service.
"So if ever there was an example of a party that is absolutely lost the plot, lost any sense of purpose then it was that debate last night".
He said after "ten years where people haven't seen their wages go up" and are "really worrying" about their bills and inflation, "what I'm not hearing from these contenders is an answer to that problem".
Sir Keir added that Mr Sunak and Ms Truss "were both serving in government; they are the architects of the of the mess that this country is in".
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Liz Truss remains favourite
Despite Mr Sunak's feisty performance, the foreign secretary remains the bookies' favourite to replace Boris Johnson.
A snap poll by Opinium, based on a sample of 1,032 voters, found 39% believed Mr Sunak had performed best compared to 38% for Ms Truss, but crucially Tory voters split 47% to 38% in favour of the female candidate.
Postal ballots are set to arrive on Tory members' doorsteps by August 5, meaning Mr Sunak is running out of time to turn things around and he needs good performances in the debates and the early hustings if he is to do so.
Opinion polls and member surveys have suggested that he trails Ms Truss in the battle to win the votes of the card-carrying Conservatives who will elect the next prime minister.
The leadership hopefuls will spend the next month campaigning to win support from the Tory party's more than 160,000 members, with the winner to be announced on September 5.
Could Boris Johnson stay on as prime minister?
More than 10,000 of those who have a vote in the Tory leadership race want Boris Johnson's name added to the ballot paper.
A petition demanding the outgoing PM is able to compete, which requires signatories to provide a Conservative Party membership number, has been supported by over 6% of those eligible to vote in the contest.
David Campbell Bannerman - a former Tory MEP, who set up the petition alongside Conservative peer Lord Cruddas - said replacing the PM would be "guaranteeing a Labour victory" at the next election.The petition, on conservativepost.co.uk, says "the membership are very upset about what has happened to our elected leader" over his forced resignation.
It adds: "I demand Boris Johnson is added to the ballot as an option for the members to vote upon in the forthcoming election."But ballot papers with Mr Sunak and Ms Truss's name on are set to be delivered to members in a week's time, and with the race already in its final stage, it is highly unlikely the party would allow Mr Johnson's to be added.
Asked whether there was any possibility of Mr Johnson being able to stay on, Chief Secretary to the Treasury Mr Clarke said, "no".