Labour-turned-Change UK MP Chuka Umunna has announced that he is joining the Liberal Democrats, despite once claiming they could not be trusted.
The politician quit the Labour Party in February this year to join the Independent Group, which later became known as Change UK.
But following disappointing results in the European elections last month, Mr Umunna left the party and became independent.
Now, the Streatham MP has said he will be joining the Lib Dems, despite previously slating the party online.
In a tweet posted in 2013, Mr Umunna wrote: "Vince Cable talks about increasing the minimum wage, but you can't trust a word the Lib Dems say."
However, he has now described Sir Vince Cable's party as being "at the forefront" of "a progressive and internationalist movement" in British politics.
"I am convinced the Liberal Democrats, as the spearhead of a broader progressive movement in civil society, offer the best chance to improve the lives of those I represent as well as countless other citizens across our country," he said.
Sir Vince said the politician would be a "great asset".
"Chuka and I have worked together effectively for many months, campaigning for a People's Vote and to Stop Brexit," he said.
"I know that he will be a great asset to our party not just on Brexit, but in fighting for the liberal and social democratic values that we share."
His decision to once again switch parties has attracted criticism.
Labour Party chairman Ian Lavery called for a by-election in Mr Umunna's seat.
He tweeted: "Three parties in as many months....who's next?
"Put your immense popularity to the good people of Streatham...let's have a PV (People's Vote) on you and your principles. #letsgoforit #byelectionnow"