Jeremy Corbyn, the left-wing head of Britain's opposition Labour Party, is set to win a leadership race with even more support than when he was first elected last year, according to a YouGov poll in The Times on Wednesday.

In the first published poll of those entitled to vote in the election, Corbyn is leading his rival, Owen Smith, by 62 percent to 38 percent, up from the 59 percent share of the vote he won last year.

The party of Tony Blair and Gordon Brown is mired in one of the biggest crises in its 116-year history after Britain voted to leave the European Union in June.

Most of the party's lawmakers responded by voting to withdraw support for Corbyn, believing that he could not win a national election, and prompting the second leadership contest in a year.

However the 67-year-old has strong support from grass-roots members, and the poll showed that those who have recently joined Labour are more likely to back his leadership.

Critics say the increasingly bitter contest is distracting the party at time when it should be pushing its priorities onto the agenda for the government's Brexit negotiations and challenging the new prime minister, Theresa May.

Some 640,500 people are eligible to vote in the Labour contest, and more than half joined the party in the last year, The Times said.

Among those who joined before May 2015, support for Smith is at 68 percent compared with 32 percent for Corbyn, according to the YouGov poll. That drops to 28 percent for Smith among those who joined between May and September.