Liberal Democrat leader Sir Vince Cable has said he "regrets" failing to pull together a Remain coalition to try and stop Brexit.
Speaking at an event to launch his party’s EU election candidates in Wapping, east London, Sir Vince said he would have been happy to campaign alongside other parties, including new pro-Remain party Change UK.
However a leaked memo from Change UK revealed there would be “no mergers, pacts or alliances” with other parties.
Sir Vince said: “I’ve got a couple of regrets about this referendum and the first is that we’re not standing on a common platform with other Remain parties to stop Brexit.
“It’s true that the Brexit parties are also divided, but we should be standing together – the millions of people in this country who voted Remain would expect us to stand together.
“It has not happened, it was not reciprocated, so we’re going our own way, but it’s a pity.”
In comments made last week, Change UK MP Chris Leslie poured cold water on the idea of forming a coalition with the Lib Dems who "come with baggage", he said.
"It just wasn't ever on the agenda," he added.
"I don't think it will ever be likely because we are starting something new.
"We are not joining the Liberal Democrats or the Green Party."
Sir Vince said his other regret was that the EU election would happen so close to the council elections, but he expected a strong local result to buoy the party in its EU campaigning.
The UK is due to leave the EU on October 31, after Brexit was delayed amid continuing Parliamentary deadlock.
It means the UK must now hold European elections on May 23, or leave on June 1 without a deal.
Sir Vince denied that the European Parliament elections would be a proxy for another EU referendum, saying a People’s Vote would still be needed because “that’s the only way of resolving the issue”.
He added: “The EU elections will give us a sense of how people feel about it but they won’t give a clear answer to that question.”
Pushed on whether his party was seeking to block the democratic will of the people and the vote for Brexit, Sir Vince said he was not leading a “fringe protest party”.
He said: “We’re a serious party, if that’s what you mean by saying we’re a party of the Establishment.
“I’ve been in government, I’ve been a Cabinet minister, so to that extent we’re not just a fringe protest party.
“We’re a serious party with something serious to say and something serious to offer and we’re not embarrassed about that.”