National MPs are arriving at Parliament this morning ahead of an emergency caucus meeting to decide if the party will change its leader.

Bay of Plenty MP Todd Muller told current leader Simon Bridges he planned to challenge him for the leadership, saying he did not have confidence that Bridges could lead National to victory in the next election.

Bridges instructed all 55 National MPs to be in Wellington today to vote on the leadership.

Political commentator Bryce Edwards said after the latest poll results, a lot of people in the National camp are drifting away from Bridges.

He told Newstalk ZB's Tim Dower it would be too tough for him to survive.

Edwards believes the difference in two political polls may have revealed shaky ground for National's economic mantra.

He said Muller will have to re-recreate the National party front bench, bring in his own supporters and try to win over his opponents.

In terms of a deputy, Edwards said Muller and Nikki Kaye are the best political duo to represent National at this year's election.

He said National desperately needs Muller - because he's more politically centrist than Bridges, and will pull National towards the middle. National has become too socially conservative under Bridges and Paula Bennett.

He said Kaye has the ability to bring voters back to the blue side - because of her urban and social liberal political style.