Quebec MP Guy Caron is joining the race to lead the NDP, bringing to three the number of candidates so far in the race to succeed Tom Mulcair.
Caron, an economist who was first elected to the House of Commons in 2011, is making the announcement today in Gatineau, Que.
The slow-starting race to replace Mulcair has been gaining steam in recent weeks, with northern Ontario MP Charlie Angus and B.C. MP Peter Julian also in the running.
A leadership debate is scheduled for March 12 in Ottawa.
Manitoba MP Niki Ashton and deputy Ontario NDP leader Jagmeet Singh are also said to be considering a bid.
A new leader is scheduled to be chosen by the end of October.