British comedian John Oliver has mocked Barnaby Joyce on late night TV, poking fun at the deputy PM’s “hypocritical” affair with his former media adviser Vikki Campion.

In a segment on Last Week Tonight, Oliver laid into Joyce over the political scandal that has dominated national headlines in recent days.

He pointed out to US viewers that Joyce opposed gay marriage in last November’s marriage equality vote due to his belief in traditional values.

“Joyce is a social conservative and opposed same-sex marriage in their referendum last year because he believes in traditional family values, and you can probably see where this is going,” Oliver joked.

“Now you might think that that is hypocritical, but in reality Joyce has such incredible family values that he can’t restrict them to just one family.

https://www.youtube.com/watch?v=DSdG99PkNKA

“The Australian media has understandably jumped on this story like a deputy prime minister with a wife and four children jumping on his 33-year-old former media adviser.”

The latest person to question Mr Joyce’s leadership was WA Nationals leader Mia Davies, who urged him on Tuesday afternoon to step down because of the “ongoing damage” he was causing.

Mr Joyce hit back by pointing out the WA Nationals have no “skin in the game” because they operate independently of the federal Nats, and have no federal members in Parliament.

Earlier in the day, he struck a similarly defiant tone by labelling the calls for him to resign a “witch hunt”.

“I am humbled by the support in my electorate and in the community,” he was quoted as saying by Fairfax Media on Tuesday.

“People are starting to see this as a witch hunt. I’m not going anywhere, I never would.”

Mr Joyce’s estranged wife was also quoted by News Corp as saying she did not want him unseated as Malcolm Turnbull’s deputy or as Nationals leader.

The report cited Mrs Joyce’s close friends as saying she has been worried that some in the Nationals party room are using the scandal to unseat the Deputy PM and claim the leadership.

In the US clip, Oliver also made fun of Peter Campion, the father of now-pregnant Ms Campion, showing a Channel Seven news clip of him saying: “I think a deputy PM on a spit would be quite a sight”.

Oliver mocked him as “the most Australian man who has ever lived”.

“In Australia, they don’t actually have Santa Claus, they just have that guy coming down your chimney and, whether you’ve been bad or good, he just beats you with a newspaper,” he said.

Oliver is no stranger to ribbing the deputy prime minister.

In 2015, the comedian targeted Joyce over his stoush with Johnny Depp where he threatened to euthanise the Hollywood actor’s two pet dogs, Pistol and Boo, after they entered the country illegally.

“I’ve got to say that’s pretty ballsy. Elected officials very rarely risk openly telling puppies to go f–k themselves,” he said at the time.

Labor frontbencher Anthony Albanese accused the government of “melting down in front of our eyes” – referencing the fact that Mr Joyce was unable to serve as Acting Prime Minister during Mr Turnbull’s trip to the US.

“The first task of the deputy prime minister is to deputise when the prime minister is not available,” he said on Tuesday.

“The Prime Minister’s away, the Deputy Prime Minister can’t do his job and hence has gone on leave. He should just leave.”