Speculation is well underway over who will vie for the leadership of the federal New Democrats, after Tom Mulcair lost the party's vote over the weekend.

Speaking to host Rick Cluff on CBC's The Early Edition, long-time B.C. MP Nathan Cullen said Monday he is thinking about it. 

"But my initial response in the last few months, when asked, has been no, that's where my feeling is right now."

"It is a 15 - 20 year commitment, I should probably not make a decision like that in 24 hours," he said. 

Cullen ran for the leadership in 2012 and placed third. The five-term MP was first elected to his B.C. riding of Skeena–Bulkley Valley in 2004. Currently, he is the environment and climate change critic and democratic reform critic

Surprised by vote

Cullen said he was surprised by the result of the vote. 

"It was quite emotional," he said.

"Just getting over the shock of what happened over the weekend. I didn't expect it."

With files from the CBC's The Early Edition and Catherine Rolfsen.