Discussions are said to involve two shadow cabinet members.
And they are separate from any taking place with leader Sir Keir Starmer’s inner circle, who kept the shock defection of right winger Natalie Elphicke a total secret.
The week before that, Dr Dan Poulter switched sides to join the Opposition benches.
One shadow cabinet member said: “The message I have been sharing with Conservatives thinking of coming over is, you will get a warm welcome. We want to build a big team.”
Meanwhile, a former Tory minister approached by The Sun on Sunday said: “I never rule anything in or out.”
Labour MPs are looking at the One Nation group, on the Tory left.
A source said members could hope to emulate Tory Shaun Woodward, who crossed the floor in 1999 and ended up serving in the Labour government.
One Labour MP said they should poach the “big five” — a defection for each of Rishi Sunak’s key pledges.
They added: “We’ve got one on the NHS, one on small boats.
“Next we need three on the economy.”
Another said: “Lots of people are having conversations.
“There are cross party relationships.”
A list being shared in Labour circles is said to contain 26 Tories who could be targeted.
One Cabinet Minister admitted “everyone’s paranoid” — and a Tory MP said: “It’s hard to predict who could be next.”
However, another senior Tory dismissed the two latest defections, as Ms Elphicke and Dr Poulter will both stand down at the Election.