At least two more Tory MPs could defect to Labour before the next general election, HuffPost UK has learned.
A handful of Conservatives are understood to have held talks with opposition officials about the possibility of switching sides.
Two MPs elected as Tories in 2019 - Christian Wakeford and Dan Poulter - have already crossed the floor in this parliament.
But it would be a hammer-blow for Rishi Sunak - already reeling from the Tories’ disastrous performance in the local elections - if any more were to follow suit before voters go to the polls again.
Whitehall sources say discussions are at an advanced stage with two more Conservative backbenchers, although no final decisions have been made.
“It’s a big deal to move from one party to another and nothing is certain until it actually happens,” said an insider.
The defection talks come as pollsters continue to predict that the Tories are heading for a heavy defeat at the next election.
Wakeford, the MP for Bury South, dramatically defected to Labour in January, 2022, over the partygate scandal.
He said: “I have reached the conclusion that the best interests of my constituents are served by the programme put forward by Keir Starmer and his party.”
Poulter stunned Westminster last weekend when he also left the Tories for Labour, blaming the government’s handling of the NHS.
The Central Suffolk and North Ipswich MP, who is also a doctor, said: “I have to be able to look my NHS colleagues in the eye, my patients in the eye and my constituents in the eye.
“And I know that the Conservative government has been failing on the thing I care about most, which is the NHS and its patients.”
He also said he believed the Tories had become “a nationalist party of the right” in recent years.