The Liberal Democrats have launched their European election campaign with a “simple” and “unambiguous” pledge to stop Brexit.
Leader Sir Vince Cable accused the Tories and Labour of a “stitch-up” and said the UK was “in paralysis”.
He called for a “people’s vote” on whether people wanted to continue with Brexit or remain in the EU.
The UK is due to leave the EU on 31 October, after Brexit was delayed amid continuing parliamentary deadlock.
It means the UK must now hold European elections on 23 May, or leave on 1 June without a deal.
But if agreement can be reached among MPs before 22 May, the UK could cancel its participation in the European parliamentary elections.
However, cross-party talks aimed at reaching consensus have yet to make significant progress.
Speaking in Wapping, east London, Sir Vince said his “exit from Brexit” catchphrase had been regarded as a “bit wacky” but was now “the mainstream” and likened their stance to the Lib Dems’ opposition to the 2003 invasion of Iraq – backed by the Tories and Labour at the time.
“At the time we were regarded as way out on a limb, unpatriotic – and we were vindicated, we were proved right. And that’s why I believe we will be right about Europe.”
But he said he regretted that the Lib Dems were not standing on a common platform with other Remain-backing parties, to stop Brexit.
“We should be standing together,” he said – adding millions of Remain-backing Britons would expect that.
“The Liberal Democrats made it very clear we were happy to work with others, it wasn’t reciprocated and we are going our own way.”
He said he expected the party to do well but added: “It is a pity and I regret that we are not doing a combined campaign.”
He described reports of a leaked document which suggests that newly formed Change UK will seek to “win over” Liberal Democrat supporters, as “unfortunate”.