No scandal seems to be able to force Australian deputy prime minister Barnaby Joyce out of office.

The Nationals leader's relationship with his pregnant partner Vikki Campion is raising more alarm bells, following allegations she was shuffled around Parliamentary jobs.

He's also been questioned about flights the pair took, and a rent-free townhouse provided to him a business friend.

But Sky News chief political reporter Kieran Gilbert told Mike Hosking the Liberal government needs the Nationals, and the Nationals need him.

"There is not really an heir apparent, there is no stellar replacement waiting in the wings. He is clearly the best retail politician they've got."

Joyce has also fended off potential expulsion over his now-denounced New Zealand citizenship.