LONDON — The British public would support a second Brexit vote by a margin of two to one if talks with Brussels break down, a new poll suggested.

In a YouGov survey of more than 10,000 people, 50 percent said that, in the event of a no-deal outcome in negotiations, they would prefer a fresh vote to MPs being handed the decision over country’s future, an option backed by just 25 percent.

Even without a breakdown in talks, support for a second vote is strong, with 45 percent backing the idea of a public vote on the outcome, 34 percent against and 22 percent unsure.

Significantly, support for a second referendum is overwhelming among supporters of Jeremy Corbyn’s opposition Labour party, with 63 percent backing the proposal, and only 18 percent against. Labour supporters would also back the Remain option in any vote by 77 percent, the poll suggests.

Corbyn and the Labour leadership have not ruled out backing a second referendum and the party is expected to face calls from members to change its policy at September’s annual conference in Liverpool.

The poll, commissioned by the Open Britain campaign group, found overall support for remaining in the EU is now at 53 percent, with Leave at 47 percent (excluding those who said they did not know.) The referendum in 2016 delivered a 52-48 victory for Leave. The poll also found strong support for the suggestion that “promises made by the Leave campaign will be broken” with 73 percent agreeing with the statement and 13 percent disagreeing.

Pollster Peter Kellner, former president of YouGov, in comments provided by the pro-second referendum People’s Vote campaign, said: “If the Brexit negotiations with Brussels break down, a two-to-one majority of voters want the public, not parliament, to decide what happens. Even people who voted Leave tend to prefer a new referendum, by 39-34 percent,” he said.