The future of opposition Labour leader Jeremy Corbyn looked shaky on Sunday after two members of his top team quit and others seemed set to follow over his handling of Britain's EU referendum.
Corbyn sacked his foreign affairs spokesman, Hilary Benn, late Saturday after Benn said he no longer had confidence in his leadership, while health spokeswoman Heidi Alexander announced her resignation on Twitter Sunday.
Media reports suggested that several other members of Corbyn's shadow cabinet would follow suit.
There is widespread anger among Labour MPs.
Many of them have been critical of the veteran socialist leader since his election last September, saying he did not fight hard enough for Britain to stay in the European Union.
The shock decision by the country to vote to leave the bloc, throwing the 28-member alliance into turmoil by becoming the first country ever to leave, was against the wishes of most Labour lawmakers.
The outcome of the vote has triggered a slump in the value of sterling and UK stocks and unleashed a fast-moving political and constitutional crisis.
Two Labour MPs tabled a vote of no confidence in Corbyn on Friday, which is expected to be discussed at a meeting of the parliamentary Labour party (PLP) on Monday.
But Corbyn gave a speech on Saturday indicating he was going nowhere and a spokesman Sunday insisted he has no intention of resigning.
"Jeremy Corbyn is the democratically elected leader of the Labour Party and will remain so," the spokesman said.
Prime Minister David Cameron resigned shortly after the results emerged on Friday morning, triggering a leadership contest in his Conservative party.
The winner will replace him by October at the latest.
But the referendum has also plunged Labour into crisis, after more than a third (37 percent) of Labour voters ignored their party's support for "Remain" and backed a Brexit.
Critics say Corbyn -- who for decades had expressed eurosceptic views -- could have done more to sway voters.
"It has now become clear that there is widespread concern among Labour MPs and in the shadow cabinet about Jeremy Corbyn's leadership of our party," Benn said in a statement.
He said there was "no confidence" in Labour's ability to win the next election, which is not due until 2020 but which he noted could now be called much sooner.
"At this critical time for our country, following the result of the EU referendum, we need strong and effective leadership of the Labour Party that is capable of winning public support so that we can stand up for the people of Britain," Benn wrote.
In her letter to Corbyn, Alexander said Britain was facing "unprecedented challenges" following the referendum and Corbyn did not have the answers.
"As much as I respect you as a man of principle, I do not believe you have the capacity to shape the answers our country is demanding," she wrote.
She added: "More than ever, our country needs an effective opposition which can hold the government to account which is capable of developing a credible and inspiring alternative to an increasingly right-wing and backward looking Conservative party."
After Benn was sacked, other Labour MPs came out in his support.
"This is sad news indeed and I cannot understand how Jeremy thinks it will help his worsening position with the PLP," Roberta Blackman-Woods tweeted.
"The Labour shadow cabinet must now act to save the Party and for the sake of the country. Otherwise we will never be forgiven," tweeted Ben Bradshaw.
Any challenger would need the support of 20 percent of the party's 229 MPs and it would then be put to party members, who were responsible for electing Corbyn last year.