Judith Collins heir to National Party throne - Chris Trotter, Trish Sherson

With Bill English stepping down as leader of the National Party, the contest has now begun to succeed him.

Political commentator Chris Trotter told The AM Show on Wednesday Judith Collins is the rightful heir.

"It's got to be Judith Collins. If I was in the National Party caucus she is the person I would be backing," he says.

"Better or for worse, [she] is seen by more and more people as an inevitable leader of the National Party at some point and it may be this point."

Political commentator Trish Sherson says it would be easier for Ms Collins to be an attack dog against the new Government.

"It would be much harder for one of the male leadership candidates to go up against Jacinda Ardern," she told The AM Show.

"Collins does have the benefit of being a woman an older woman."

Mr Trotter agrees, and says Ms Collins would be a formidable Opposition leader and it would a thrilling battle against Ms Ardern.

"For all those aficionados of Game of Thrones, it would be Daenerys Targaryen versus Cersei Lannister," he says.

"A grudge match to beat all grudge matches."

However if Ms Collins does decide to run, she may face tough competition.

On Wednesday, rival contender Simon Bridges said he "may well have something to say later today".

"At the moment I am talking to colleagues we'll just sort of see what happens it may be that I have more to say later today," Mr Bridges told media.

Newshub.