Winston Peters isn't ruling out working with National under new leadership.

Todd Muller made a shock resignation this morning, and National ruled out working with New Zealand First under the leadership of Muller's predecessor Simon Bridges.

Peters told Heather du Plessis-Allan he's previously worked with anyone he could.

"Personally, I don't rule people out or rule people in, I never say never. I rule out policies and I rule out principles that I see as damaging to this country's future."

On the matter of a Cook Islands travel bubble, Peters does not know if we are set to go. 

The Prime Minister held held discussions overnight with the Cook Islands Prime Minister - on the possibility of opening an "air bridge" between our nations.

Cook Islands deputy prime minister Mark Brown earlier told Newstalk ZB they have the best health measures in place to keep both countries safe from Covid-19.

He says he's hopeful both countries health officials will be able to agree on the protocols for this to go ahead quickly.

However, a spokesperson from Jacinda Ardern's office says no dates are set yet, and speculation is very premature.

Peters says that they just want to ensure that everyone can be safe, but he cannot see any obstruction.

"If we can't remove this barrier, there's something wrong with us." 

He says that it seems we are stalling for no good reason. 

On his recent health issues, Peters says that he was "as crook as a dog", and that the doctors told him that he needed to come in - and the timing of the recess meant he had the chance to. 

Now, he feels fine.  

"All has ended up seriously well."