Boris Johnson would give the Conservatives an eight point lead in the polls if he becomes party leader a new survey has found - but only after he delivered Brexit.
According to a YouGov poll published on Tuesday, the Tories would be on 28% of the vote ahead of the Lib Dems on 20%, Labour on 17%, The Brexit Party on 14% and the Greens on 9%.
But the survey found that the Tories would be neck-and-neck with the Lib Dems with Johnson as leader at an election held before Brexit.
The poll for Britain Elects suggested a pre-Brexit general election would see the Conservatives and Lib Dems on 23%, The Brexit Party on 21%, Labour on 17% and the Greens on 8%.
The questions were asked on the assumption Jo Swinson was Lib Dem leader.
According to the poll, Johnson is seen as more likely (35% - 5%) than his leadership rival Jeremy Hunt to deliver Brexit by October 31
But 50% of voters also believed Johnson was “most likely to promise anything to be prime minister” compared to just 16% who thought the same of Hunt.
The two contenders to succeed Theresa May will appear on a live ITV debate at 8pm on Tuesday which could help to decide the outcome of the contest.
Johnson will hope to use the occasion to seal his position as the clear frontrunner, with polls giving him an overwhelming lead among party members.
For Hunt, the foreign secretary, it potentially offers a final chance to turn around a contest in which he has been the underdog throughout.
There has been frustration in the Hunt camp at the reluctance of his rival to engage in direct debate.
Ballot papers started going out last week to the party’s estimated 180,000 members, and many will already have voted, meaning that the potential for the debate to alter the course of the contest may be limited.