Rishi Sunak “neck and neck” with Liz Truss in the Tory leadership race, a supporter of the former chancellor has insisted.
Conservative MP Kevin Hollinrake cast doubt on the accuracy of polls showing Truss was the runaway frontrunner.
Speaking to Sky News, he said the contest was far from “cut and dried”.
It would be a huge shock in Westminster if Sunak defeats Truss, with the foreign secretary assumed to have the contest sewn up.
Voting will close contest at 5pm on Friday. A YouGov survey of Tory members in August showed held a comfortable 32-point lead.
But Hollinrake said: “I’ve seen some of the polls and national polls.
“I think it’s quite hard for pollsters to determine who is a Conservative member and who is not because there’s not an open database.
“But I know who mine are. I polled my 700 members, 239 of them responded, so about a third of them responded, and Rishi got an eight-point lead.
“And I’ve seen similar kind of polls around different constituencies around the country. So I don’t think he’s cut and dried. I think he’s probably neck and neck.”
Sunak and Truss made their final leadership pitches to Conservative members at a leadership hustings in London on Wednesday, with the debate dominated by the rising cost of living.
Truss claimed there would be no new taxes or energy rationing if she became prime minister, and dropped further hints about cost-of-living support this winter.
“I will also deliver immediate support to ensure people are not facing unaffordable fuel bills. I will be robust in my approach,” she said.
“But it isn’t right to announce my entire plan before I have even won the leadership and got my feet under the table.”
Sunak has sought to portray himself as the candidate with a more realistic assessment about the way to approach the economy, with tax cuts not expected immediately if he becomes leader.
Though voting closes on Friday, the result will not be announced until Monday.
Johnson and his successor will then go to Balmoral rather than Buckingham Palace for the appointment of the new prime minister, in a break from tradition.
The Queen will receive Mr Johnson on Tuesday September 6 at her Aberdeenshire home, where he will formally tender his resignation.
This will be followed by an audience with the new Tory leader, where she or he will be invited to form a government.