London: Thousands gathered on Saturday to march through London calling for a second European Union (EU) referendum, as MPs search for a way out of the Brexit impasse.

Demonstrators from the “Put It To The People” campaign will march from Park Lane to Parliament Square, followed by a rally in front of the Parliament, the BBC reported.

It comes after the EU agreed to delay the UK’s departure from the EU.

Prime Minister Theresa May has said she will ditch plans for another vote on her Brexit deal if enough MPs don’t support it.

Unless that deal is passed by the MPs, the UK will have to come up with an alternative plan or else face leaving without a deal in April.

Meanwhile, a record-breaking online petition on Parliament’s website calling for Brexit to be cancelled by revoking Article 50 has attracted more than 4.18 million signatures.

Liberal Democrat MP Layla Moran said the petition could “give oxygen” to the campaign for another Brexit referendum.

Speakers at the rally will include Labour party’s deputy leader Tom Watson, Scotland’s First Minister Nicola Sturgeon, London Mayor Sadiq Khan, Independent MP Anna Soubry and former Attorney General Dominic Grieve.

Sturgeon said now was “the moment of maximum opportunity” to avoid a no-deal Brexit.

Watson is expected to promise to back May’s deal if she agrees to hold a referendum on it.

Soubry said: “It’s intolerable the situation that we’re in and I’m afraid Theresa’s the problem.

“I’m not saying the government should go because that’s the last thing we want, but I think she has to go and we need some temporary prime minister who can reach out, put the country first, get this back to the British people – that’s what we’re all marching for today, a people’s vote.”

If May’s deal is approved by MPs next week, the EU has agreed to extend the Brexit deadline until May 22. If it is not – and no alternative plan is put forward – the UK is set to leave the EU on April 12.

In a letter to all MPs on Friday evening, May offered to talk to them over the coming days “as Parliament prepares to take momentous decisions”.

Children’s Minister Nadhim Zahawi said that failing to support May’s deal would lead to a “meltdown in our politics, not just for the Conservative party but for all parties”.

The march comes as the pro-Brexit March to Leave, which started in Sunderland a week ago, continues towards London.