Prime Minister Theresa May must resign or the Conservatives should force her out following the party’s heavy local election losses, Iain Duncan Smith has said.
The former Tory leader called Mrs May a “caretaker PM”, describing attempts to find a deal with Labour as “absurd”.
It comes after the party suffered its worst local election result since 1995.
Other senior Conservatives have urged Tory MPs to compromise with Labour to ensure Brexit is delivered.
But Mr Duncan Smith, a leading Brexiteer in the party, said many Conservatives would refuse to back a deal reached between the two parties.
He said Mrs May must announce her departure “very soon” in the wake of the party’s heavy losses.
If she did not go, the 1922 Committee of backbench MPs would have to force her to do so, he said.
The committee recently narrowly agreed not to change the party rules to allow another confidence vote to take place that could oust Mrs May.
However, some senior Conservatives believe that in the wake of the council defeats, the mood on the 1922 executive committee has changed.
Elections were held on Thursday for 248 English councils, six mayors, and all 11 councils in Northern Ireland – where counting continues. No elections took place in Scotland or Wales.
Labour failed to make expected gains in the elections, instead losing 82 seats, while the Liberal Democrats benefited from Tory losses, gaining 703 seats. The Greens and independents also made gains.
Speaking on LBC Radio, Mr Duncan Smith said allowing “caretaker PM” Mrs May to make fundamental decisions about the future would be a “big mistake”.
Both Mrs May and Labour leader Jeremy Corbyn have insisted they will push ahead with talks seeking cross-party agreement on leaving the EU, following the local election results.
Mrs May said it was clear the public wanted “to see the issue of Brexit resolved”.
Health Secretary Matt Hancock said the party needed to listen to the results and be “in the mood for compromise”.
Speaking to BBC Radio 4’s Today programme, Mr Hancock said the nation wanted MPs to “get on, deliver Brexit, and then move on”.
Scottish Tory leader Ruth Davidson echoed Mr Hancock as she reflected on the Conservatives’ and Labour Party’s “almighty kicking” in the local elections.
“The solution doesn’t lie in the trenches of one extreme or another – of overturning the referendum, or of crashing out with no deal,” said Ms Davidson, who was speaking at the Scottish Conservatives conference in Aberdeen.
“It lies in those colleagues currently round the table taking the difficult first steps towards each other.
“So I say to the negotiating teams of our party and the Labour Party, who are currently locked in talks – get Brexit sorted, get a deal over the line and let Britain move on.”
The UK was due to leave the EU on 29 March, but the deadline was pushed back to 31 October after Parliament was unable to agree a way forward.
Speaking to BBC Radio 4’s Today programme, Mr Hancock said the Tories might have to move towards Labour’s proposal of a permanent customs union – in order to solve the impasse in Westminster.
Mrs May’s government has previously ruled out remaining in a customs union after the UK leaves the EU, arguing it would prevent the UK from setting its own trade policy.
Labour has said the EU may show flexibility over the issue and allow the UK “a say” in future trade deals.
Mr Hancock suggested “coming up with something in-between”, and called for “an open dialogue in which we can make an agreement”.
But Mr Duncan Smith said a customs union was “the worst of all worlds because you lose your decision-making capacity”.
‘Find a solution’
Foreign Secretary Jeremy Hunt said there was a “glimmer of hope” that a compromise between the Conservative and Labour “core-voters” could be reached.
“If we can find a solution that delivers the benefits of the customs union without signing up to the current arrangements, then I think there will be potential,” he said.
He added that while he supported the withdrawal deal reached between the EU and Mrs May, there might be things that could be done to make it “more acceptable” to Labour without compromising on the “things that we think are essential”.
But he also warned that a customs union would not be a “long-term solution”.
Shadow Brexit secretary Sir Keir Starmer said Mr Hunt’s remarks on a customs union provided “yet more evidence” that many in the cabinet believed the “most important thing right now” was the race to be Mrs May’s successor.
Labour’s MP for Redcar, Anna Turley, also reacted to Mr Hunt’s comments that a customs union was not a long-term solution, tweeting: “This is why we can’t trust the Tories by doing a deal stitched up in Number 10 which they will seek to unravel under their next leader.”