Angela Eagle has said she will stand to trigger a Labour leadership contest if Jeremy Corbyn does not step down of his own accord.
The former shadow business secretary stepped down in a wave of resignations last week and called for Mr Corbyn to resign.
Ms Eagle told Sky News that Mr Corbyn was “not properly engaged – with even the deputy leader of the party”.
“There are many people – MPs, party members up and down the country, asking me to resolve this impasse”, she said, speaking outside her home.
Mr Corbyn has since struggled to fill all his shadow cabinet posts after dozens of MPs on his top team said they would no longer work with him.
Rebel Labour MPs are now understood to be split on whether or not Ms Eagle or former shadow work and pensions secretary Owen Smith should the candidate to take him on.
A recent poll however suggests that Mr Corbyn would however still beat both in a leadership contest.
The same poll shows his esteem amongst Labour members having fallen sharply since last month, however – with rebels optimistic they can make ground.
176 MPs have already voted ‘no confidence’ in Mr Corbyn in a secret ballot, with just 40 backing him.
The attempted coup has however lost momentum in recent days, with few further developments since the 'no confidence' vote.
Ms Eagle or Mr Smith would have to gain nominations from MPs in order to stand.
Mr Corbyn was elected by a landslide of Labour members, supporters, and trade unionists just last September.
He has refused to step down, citing his significant mandate from the party membership.
The party has doubled in size since he became leader but has struggled to sustain the levels of support it had amongst the wider electorate in the last parliament.
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