Liz Truss has increased her lead over rival Rishi Sunak to 34 points, according to a YouGov poll of Conservative Party members.
It shows 60 percent of the party members polled between July 29 and August 2 say they intend to vote for Ms Truss.
That number is up from 49 percent in the period July 20 to 21, which was immediately after the final two were announced.
Support for Mr Sunak, the former chancellor, has dropped in the poll, from 31 percent to 26 percent over the same period.
Liz Truss and Rishi Sunak
PA
A total of 60 percent of Tory Party members polled between July 29 and August 2 say they intend to vote for Ms Truss
Kirsty O'Connor
The rest of the 1,043 Conservative party members polled say they are undecided or will not vote.
A total of 83 percent of those who currently say they intend to vote for Ms Truss also say they have made up their mind.
While 17 percent say they might still change their mind, and 29 percent of Mr Sunak’s supporters say they might still vote differently, according to YouGov.
A Ms Truss campaign source said on the latest YouGov polling: “This reflects exactly what we are seeing with members around the country.
“Members are making up their mind, and they are supporting Liz.
“Her bold and ambitious plan for the country and economy is uniting Conservatives right across our nation.
"But we are certainly not complacent, Liz is fighting for every vote, meeting as many members as possible.”
While a separate poll, conducted by Techne suggests that Mr Sunak has narrowed the gap between himself and Ms Truss.
The poll of 807 Conservative members had the Foreign Secretary leading by just five points.
