Chuka Umunna used his first Liberal Democrat conference speech to issue a blistering attack on “illiberal” former boss Jeremy Corbyn.
Mr Ummunna left Labour to launch what was originally called Change UK in February, but after terrible results in the European elections he joined the Lib Dems.
At the party’s conference in Bournemouth yesterday he said Labour “likes to think of itself as a champion of liberal values”, but it wasn’t under Mr Corbyn’s leadership.
He said: “You cannot be a champion of liberalism if you are currently subject to a formal investigation by the Equality and Human Rights Commission for institutional racism against Jewish people.
“You cannot be a champion of liberalism when your leader’s supporters think it is acceptable to abuse, vilify and deselect anyone who dares to question the leader.
“And you cannot claim to be liberal when the political editor of the BBC needs to take a bodyguard to your conference.”
Mr Umunna criticised the Labour leader’s foreign policy positions, saying he acted as “an apologist for a hard-right Russian government that thinks it’s OK to poison people on British soil”.
The Lib Dem MP also criticised the prime minister’s approach to Brexit, saying he is “seeking to force through a catastrophic no-deal”, and “flouting the rules at home and abroad”.
He said Boris Johnson and the Brexit Party leader Nigel Farage were “the peddlers of hate and division”.
Instead, he praised his leader, saying Ms Swinson could “build and breathe a progressive breath of fresh air” into UK politics.
Mr Ummunna later faced questions over his party’s commitment to cancel Brexit without a second referendum while at the same time insisting the SNP could not declare Scottish independence if the party wins a Holyrood majority.
He said: “I think that’s a different issue, let’s see if she (Nicola Sturgeon) were to get a majority.”
Mr Umunna added that the issue of Scottish independence was a “settled issue”.