B.C. MP Nathan Cullen joins race for NDP leadership

NDP MP Nathan Cullen is running for the federal party's leadership, he confirmed Friday, kicking off a weekend with three expected candidacy declarations.

Cullen is the third official candidate, following former party president Brian Topp and Quebec MP Romeo Saganash.

It's expected Ottawa MP Paul Dewar will announce his candidacy on Sunday, with an announcement scheduled for that afternoon a few blocks from Parliament Hill.

A Nova Scotia pharmacist is also expected to declare his candidacy this weekend. Martin Singh is the president of the federal NDP's faith and social justice commission, and the riding president for Sackville-Eastern Shore.

Speaking to Rosemary Barton on CBC's Power & Politics, Cullen said he's comfortable being an underdog, joining the race after Topp has already attracted the support of high-profile NDP members like former leader Ed Broadbent and former Saskatchewan premier Roy Romanow.

MPs Niki Ashton, Robert Chisholm, Peter Julian, Pat Martin, Thomas Mulcair and Peggy Nash are still deciding whether they'll throw their hats into the ring.

Cullen represents the northern B.C. riding of Skeena-Bulkley Valley. He was first elected in 2004 and has served as the NDP's natural resources critic, where he was a vocal critic of a plan by Enbridge to extend its Northern Gateway pipeline through his riding.