They say former NDP members Chris Mitchelmore and Dale Kirby, who quit the caucus in October in a public leadership spat, will join the Liberals.
Both Kirby and Mitchelmore have sat as Independents since the dispute.
They left the NDP caucus after pushing for a leadership review to help renew the party and attract new members.
NDP Leader Lorraine Michael said she felt betrayed by the move.
Two Progressive Conservative government members have also crossed the floor to the resurgent Liberals over the past year.
Premier Kathy Dunderdale quit last month over questions about her leadership.
Former finance minister Tom Marshall has taken over as premier and has said he won't run in a leadership race expected later this year.
Kirby and Mitchelmore did not answer requests for comment.
With Kirby and Mitchelmore, the Liberals would have 11 seats in the legislature compared to 34 Tories and three New Democrats.
An election is expected sometime in 2015.