Former prime minister and National Party leader Sir John Key says the party has his support but it's up to the current leadership to deal with the fallout following Jami-Lee Ross' departure.

Key, speaking at a business event in Auckland, was asked today about the issues the party has been grappling with after Ross was identified as the person who leaked information about leader Simon Bridges' travel expenses to the media.

"I don't really comment on that now. I mean, obviously I'm a paid-up member of the National Party and I've always said I bleed blue and I'll do that. But it's for Simon Bridges and [party president] Peter Goodfellow to really deal with those issues. They have my support but in the end it's for them to come up with solutions," Key said.

Key was asked if National was going to be okay in the aftermath of the scandal in which Ross claimed donation fraud, laid a complaint with police and admitted to affairs before going into mental-health care.

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"I'm a long-term believer in the National Party ... We've got a great team, we've got a lot of very good ideas, and I think fundamentally we're in good shape," Key said.

Ross quit the National Party and was expelled from caucus last month after he went rogue following being publicly named as the mostly likely source of the leak.

After a tumultuous couple of weeks for both Ross and the party, he has retreated to the care of friends and is taking a break from politics.

National is currently considering an offer from Ross to use his proxy vote in Parliament.