Simon Bridges' phone call with Air NZ boss and possible National candidate Christopher Luxon

National leader Simon Bridges has had a chat with Christopher Luxon after the Air NZ boss signalled a possible political future with the National Party - but he won't say who called whom.

Luxon's future with National has been the subject of much speculation since he said on Wednesday last week that he will leave Air NZ at the end of September.

He told Newstalk ZB the following morning that he was interested in a future in politics, and his natural political home would be the National Party.

He said he was not "John Key 2.0", but added that the former Prime Minister and Air NZ board member had encouraged him to stand for National.

The speculation escalated at the weekend when Christchurch businessman Steve Brooks took out a half-page ad in the Herald featuring an image of John Key morphing into Luxon, and hashtagged #LUXON2020 and #NATIONAL2020.

This morning Bridges said he knew nothing about the ad, didn't know Brooks, and didn't know the story behind the ad, adding that it probably breached electoral law because it was not authorised by the party.

Under the law, any ad that promotes voting for a particular party has to be signed off by that party.

The Electoral Commission is now investigating.

Bridges said he spoke to Luxon at the end of last week but was not actively courting him.

He wouldn't say if he had initiated the call.

"I didn't over analyse that part of it ... You know how many calls I do a day? We might be calling 50 or 60. I don't think a whole lot about who rings who. I appreciate how exciting it is to you, but that's not uppermost on my mind.

"Chris is a talented guy, he's had a distinguished business carrier. He's a good guy. Now it's a case of waiting to see what happens."

Asked whether Luxon would make a good party leader or Prime Minister, he said: "Let's see what happens. Let's be fair to the guy and let's see if he gets to Parliament first."

He said he knew Luxon personally, as well as from his time as Transport Minister, but he would not say whether they had talked about Luxon's future prospects with National.

Luxon is the chair of the business advisory group that advises Prime Minister Jacinda Ardern, and Ardern has said she was happy for him to continue in that role until he leaves Air NZ in late September.

She had no concerns about whether Luxon might run for the National Party in the future.

"Obviously he has a role still to fulfill at Air NZ and I imagine his mind will rightly be on that through to September," Ardern said.

Luxon has said it was not an issue to indicate support for National while serving on the business advisory council.