Two members of Britain's main opposition Labour Party submitted a motion of no confidence in their leader, Jeremy Corbyn, on Friday after the country voted to leave the European Union at a referendum - something Corbyn had campaigned against.
The motion, submitted by lawmaker Margaret Hodge and backed by colleague Ann Coffey, calls for a debate on Corbyn's leadership among the party's parliamentary representatives when it next meets on Monday. If supported at a later secret ballot, it could then trigger a leadership contest.
Several Labour members have criticised Corbyn, who was elected leader last year on a wave of enthusiasm for his left-leaning agenda, for failing to persuade voters in his party's heartlands in northern England and elsewhere to vote to remain.
Millions of them voted in favour of leaving the bloc, often swayed by the "Out" campaign's arguments on immigration.
"In a leader you need somebody who can communicate a message and inspire confidence in that message and I think he failed on both counts during the referendum campaign and therefore I don't think he should be leader of the party," Coffey told Reuters.
"I will say to people, you can win the election or you can have Corbyn as leader but you can't have both."
Corbyn voted no to the EU's predecessor in a 1975 referendum, but campaigned for a 'Remain' vote at Thursday's ballot.
"What we saw yesterday was swathes of Labour voters simply not voting Labour. Jeremy Corbyn could not connect with the people we needed to attract," Hodge told Sky News.