And if you do, you should stand with me," Sunak said, referring to what he described as 30 years of political short-termism.
"It may be helpful, but it won't be sufficient" to help them win the next election.
Chris Hopkins, political research director at the polling firm Savanta, said he could not see how Sunak could win.
Cabinet ministers have given speeches to sparsely populated rooms and some party members have openly talked what they may do in opposition.
Writing by Elizabeth Piper; editing by Kate Holton and Philippa FletcherOur Standards: The Thomson Reuters Trust Principles.
Persons:
Rishi Sunak, Sunak, Goldman Sachs, Andy Street, Suella Braverman, pollsters, John Curtice, Chris Hopkins, Savanta, Liz Truss, Nigel Farage, Steve Tuckwell, Elizabeth Piper, Kate Holton, Philippa Fletcher
Organizations:
Conservative, Conservatives, Labour, University of Strathclyde, European Union, Republican Party, London's Labour, Thomson
Locations:
MANCHESTER, England, Manchester, British, Birmingham, West Midlands, United States