Boris Johnson has insisted he will stay in office, despite a growing Tory revolt against his leadership.
At Prime Minister’s Questions, he said he had a “colossal mandate” from the 2019 election and would “keep going”.
It comes as 21 Tories have quit government or party positions, with other backbenchers withdrawing their support.
Labour’s Sir Keir Starmer said the Conservatives had become a “corrupted party defending the indefensible”.
Mr Johnson’s premiership has been plunged into crisis following the dramatic resignations of Chancellor Rishi Sunak and Health Secretary Sajid Javid.
They quit within minutes of each other on Tuesday, following a row over Mr Johnson’s decision to appoint Chris Pincher deputy chief whip earlier this year.
Their departures have triggered a wave of further departures, with Justice Minister Victoria Atkins among the ministers quitting on Wednesday.
At PMQs, Sir Keir took aim at ministers who have resigned in recent days, saying their decision not to quit before now showed they lacked a “shred of integrity”.
And the Labour leader rounded on those who have stayed in post, mocking them as a “Z list cast of nodding dogs”, keeping the PM in power.
He added they were “only in office because no-one else is prepared to debase themselves any longer”, calling them the “charge of the lightweight brigade”.
Tory backbencher Gary Sambrook accused the PM of blaming other people for his mistakes and was applauded after calling on him to resign.
Fellow backbencher David Davis, who dramatically called on Mr Johnson to step down in January, repeated his plea for him to quit before “it becomes impossible for government to do its job”.
But Mr Johnson defied calls for him to go, adding he would “continue to deliver on the mandate I was given”.
“The job of a prime minister in difficult circumstances, when he’s been handed a colossal mandate, is to keep going – and that’s what I’m going to do.”