Labour’s deputy leader Tom Watson has called on his party to “embrace” European elections in May, as well as the possibility of a general election, saying that if it goes into either contest pledging a confirmatory referendum it can beat the Tories.

His upbeat pre-election rallying call comes as MPs prepare to vote again on Monday on a second referendum, after the plan to hold one on any Brexit deal that passes through parliament won the most votes of any option considered by MPs in last Wednesday’s series of indicative votes.

Writing on theguardian.com, Watson says he is gearing up local members to select Labour candidates ready for the elections.

While he emphasises his respect for Labour MPs and members opposed to a referendum, he says the party has now come together on a policy “that can unite our members, voters, MPs and yes, the leadership too.”

Referring to Labour commitment to a policy under which any deal would have to be confirmed in a people’s vote he says: “This is a compromise position that provides a clear path to break the deadlock. Whether you voted leave, like the majority of people in my area did, or whether you voted remain, the current parliamentary paralysis works for no one.

“We now have until April 12th to either agree a new path to a viable Brexit deal, with an extension to Article 50 that means taking part in European elections, or crash out with no deal.

“I think Labour should embrace European elections just as we should welcome a general election that might get rid of this broken government. If we go into either contest with a positive policy on Brexit and say any final deal must be put back to the people, I am confident Labour can win. We already have a fund raised by local parties to pay for the campaign and I’ve asked our national executive committee to develop a plan to get grassroots members involved in selecting candidates.”

While supporters of a second referendum accept that the idea may not win majority support in the House of Commons on Monday, they believe it could still do so when tabled in the form of an amendment to any motion to approve a deal, or to legislation that will be needed to implement any withdrawal agreement.

Under the plan to be voted on Monday, drawn up by the Labour MPs Peter Kyle and Phil Wilson, MPs would vote for a Brexit deal conditional on it then going to the country for a public vote, with Remain being the alternative on the ballot paper.

Watson’s comments come as leading Remainers in parliament are increasingly eyeing the European elections as an opportunity to mobilise those who want a public vote in order to keep the UK in the EU, following the march by one million people in support of a referendum last weekend.

He says Tory supporters, MPs and ministers, are fearful of European elections. “The Tories are right to be frightened of elections. Their internal war over Europe, waged for the last 30 years, has led the country to this point. They’ve messed up Brexit which has gone from chaos to national humiliation and are completely incapable of providing the leadership we need.”

By contrast Labour should relish them. “Our values have always been internationalist and outward-looking. The biggest gains we made in 2017 were among young people who share those values and want to “build bridges not walls”. It falls to Labour to develop a modern programme of change to address the root causes of why 52% voted for Brexit.”

Facebook Twitter Pinterest 67% of those polled disapproved of Jeremy Corbyn’s handling of Brexit. Photograph: Ben Birchall/PA

His intervention comes as the latest Opinium poll for the Observer reveals the Tories have lost their small lead over Labour amid the Brexit chaos. Labour and the Tories are now neck-and-neck on 35% of the vote.

Theresa May’s lead over Jeremy Corbyn, when voters are asked who would be the best prime minister, has halved since last month. Her lead has dropped from 15 points at the end of February to 7 points in the latest poll.

Both leaders continue to meet with deep disapproval over their handling of Brexit. Corbyn’s net approval ratings on Brexit continue to slide, hitting an all-time low of minus 53%, with 14% approving and 67% disapproving. Perception of Theresa May’s handling of Brexit has improved slightly since last week. She now has a net approval on Brexit of minus 38%, with 23% approving and 61% disapproving.

In the event of May resigning, Boris Johnson was the only leading candidate who had a lead over Corbyn when voters were asked which would make the best prime minister, with 25% backing Johnson and 24% backing the Labour leader.

Facebook Twitter Pinterest Boris Johnson: 25% of voters backed him for prime minister. Photograph: Leon Neal/PA

Adam Drummond, from Opinium, said: “Neither party leader gets good marks in terms of their overall approval rating or how voters think they have handled Brexit and, on the question of who would be the best prime minister, ‘none of these’ is rapidly approaching 50%.

“This lack of enthusiasm extends to Theresa May’s possible replacements as well. Boris Johnson is the only potential Tory leader we tested who beats Jeremy Corbyn on the ‘best prime minister’ question (albeit by 1%).”

Opinium polled 2,008 adults online between 28 March and 29 March.