Liverpool politician Luciana Berger has joined the Liberal Democrats.
Ms Berger initially stood as an independent since becoming one of seven Labour MPs to resign from the party in February over its handling of antisemitism.
Prior to quitting Labour, she had faced two no-confidence motions in the Wavertree constituency that she has represented since the 2010 General Election.
Shortly after leaving, Ms Berger joined the newly-formed Change UK party but announced on Thursday her intention to become a Liberal Democrats member.
“This is a moment of national crisis,” she told the Evening Standard.
“The Liberal Democrats are unequivocal in wanting to stop Brexit and are committed to securing Britain’s future as a tolerant, open and inclusive society.
“I am joining Jo Swinson and the Liberal Democrats today, in the national interest, to offer a vital, positive alternative to [Boris] Johnson and [Jeremy] Corbyn and help build a future that our country deserves.”
However the move has been met with condemnation from the Wavertree branch of the Labour party, who have pointed out the Lib Dems’ poor local turnout.
A statement from its chair Nina Houghton said: “Berger now represents only 6% of Wavertree constituents – those who voted Lib Dem in the last election.
“She is ignoring the 80% of Wavertree voters who voted Labour.
“She has not supported the Labour Party for some time, but has not had the courage to resign and face a by-election.
“If she truly believed in democratic values she would have done this long ago.”