OTTAWA - Nathan Cullen has become the third candidate to jump into the federal NDP leadership race.

The 39-year-old MP from northern British Columbia is billing himself as an anti-establishment contender who will put an end to Prime Minister Stephen Harper's brand of aggressively partisan politics.

But his pitch is also aimed at denting the lead of perceived frontrunner Brian Topp.

Topp has racked up endorsements from an impressive roster of NDP luminaries, including former leader Ed Broadbent and former Saskatchewan premier Roy Romanow.

Just hours before Cullen announced his leadership bid, Topp introduced his latest supporter -- veteran Vancouver MP and deputy NDP leader Libby Davies.

Quebec MP Romeo Saganash has also declared his intention to seek the leadership and Ottawa MP Paul Dewar is expected to take the plunge on Sunday.