More than a third of Tory voters who backed the party in the last general election no longer believe Boris Johnson is the best candidate to be prime minister.
While 63% of Conservative voters at the last election polled by YouGov still back the prime minister, 37% no longer support Johnson over his Labour opponent.
Instead, 28% of voters from the last general election are “not sure”, with 7% moving to the leader of the opposition.
By contrast, 72% of Labour voters last year back Starmer as the best candidate to be prime minister, compared to just 4% who support Johnson. 22% are yet to make up their mind.
The YouGov polling also found 40% of the public back Labour (up three points), 37% support the Tories (down one), 5% support the Lib Dems (no change) and 6% support the SNP (no change).
The number of people who think it was right to leave the EU has also dropped by 1% to 38% – with 50% thinking it was the wrong decision and 12% not knowing.
The Greens are polling on 5% (down one point) and the Brexit Party remain on the same figures. Plaid Cymru is on 1%.
YouGov questioned 1,696 adults between November 26 and 27.