The shadow Brexit secretary, Keir Starmer, has said Labour is the party of remain and called for unity ahead of a cross-party meeting to discuss tactics to prevent a no-deal Brexit.

Starmer said Labour’s position on Brexit had been clear for many months: the party would put any outcome to a referendum and in that referendum Labour would campaign for remain.

“Jeremy Corbyn has very clearly said any outcome now must be subject to a referendum and we would campaign for remain,” he told BBC Radio 4’s Today programme.

Starmer called on opposition leaders to agree to “a plan everyone can coalesce around”. He said the purpose of Tuesday’s meeting was to have “a pretty frank discussion” on how to prevent a no-deal Brexit.

“What we’ve seen in the last few weeks is that the prime minister really hasn’t got a negotiating strategy. That makes no deal more likely, which will be hugely damaging.”

Asked if a vote of no confidence plan, with Jeremy Corbyn becoming caretaker prime minister, was dead in the water, Starmer told Today: “No, but I think it’s important today that we pull people together and agree if we can a plan.”

He added: “I was very supportive of the measures earlier this year to pass legislation to prevent no deal and I’m very supportive of them now. I think they’re direct, I think they’re effective and I want something with a legal edge, because with a vote of no confidence it goes into the questions of conventions, who does this, who does that.

“The two aren’t mutually exclusive of course – you can do the two together – but I think there’s a strong feeling and I know Jeremy Corbyn is keen to do anything that does prevent a no-deal Brexit, but we need something with bite, we need something effective and we need to do it straight away when we come back.”

The Liberal Democrat leader, Jo Swinson, said she was “not precious” about who a caretaker prime minister would be following a successful vote of no confidence, but she did not believe Corbyn was the right choice.

Speaking on BBC Radio Scotland’s Good Morning Scotland programme, she said: “If there are others, I am open to hearing others … Anybody that could command a majority in the House of Commons to avoid us crashing out without a deal if the legislative approach, which I think is the strongest and best way forward, that doesn’t work.”

The shadow Brexit secretary said he opposed any move by Boris Johnson to suspend parliament to push through a no-deal Brexit. “The idea of shutting down parliament because you think parliament would defeat you if it was asked to decide something as serious as no deal is completely unacceptable,” he said.

The Green party MP, Caroline Lucas, echoed Starmer, tweeting that MPs would not be “bullied” into a no-deal Brexit. She said: “Boris Johnson’s intentions are clear: suspending parliament, a crash-out Brexit and blaming MPs for the chaos.

“We will not be bullied. We will not surrender parliamentary sovereignty to the rightwing cabal in No 10. MPs must unite to stop this abuse of executive power.”