Change UK received just 3.4 percent of the vote in the Euros on May 23.
A Lib Dem leadership candidate is read highly critical comments about the party made by the MP who recently defected to them.
Unfortunately for Umunna, there is a massive trail of embarrassing tweets and Facebook posts, some as recent as April 2017, where he slams the Lib Dems for enabling austerity whilst in coalition with the Tories. "There's been major splits in the two main parties and our door is always open".
Reports from the press conference suggested more MPs could follow Mr Umunna and join the Lib Dems this weekend, and not just former members of Change UK.
Sources close to new Liberal Democrat MP Chuka Umunna have said that he does not expect to take a policy portfolio immediately, but would be open to taking one once the Lib Dem leadership election between Ed Davey and Jo Swinson has concluded.
"Labour and Tories are committed to facilitating Brexit. the Liberal Democrats are not", Umunna said in a statement released by the party, which has now increased to 12 the total seats it holds in Britain's 650-seat lower house of parliament.
"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", Mr Cable added.
"This proves that the Liberal Democrats are the rallying point for those who are opposed to Brexit, want to tackle the climate emergency and want to stand up to the forces of nationalism and populism".
Umunna, a former business spokesman for Labour who clashed with its leader Jeremy Corbyn, was one of seven politicians who left Labour and joined six pro-EU Conservatives to form Change UK in February.
It pledged to push for any Brexit deal negotiated by the government to be voted on at a referendum - or "People's Vote" - in which it would campaign for the United Kingdom to remain in the EU.
The political grouping was deserted by more than half its lawmakers, including Umunna, on June 4 after receiving little public support in European Parliament elections, which instead brought big gains for the Lib Dems and the new anti-EU Brexit Party.
"Put your vast popularity to the good people of Streatham...let's have a PV (people's vote) on you and your principles".