Who will take responsibility for Joyce?

Clearly it won't be Joyce himself, who chose to call his own prime minister "inept" and is refusing to resign.

Either Prime Minister Malcolm Turnbull has to back away from his stinging criticism of his deputy, or the Nationals have to cut loose a man they are strongly backing.

Neither looks likely, so what looks to be an irreparably-damaged relationship at the top of the government is going to drag on.

Regardless of the rights and wrongs, Joyce's affair with a staffer and the fallout from it has consumed the government for 10 full days.

Sussan Ley lasted 10 days before quitting the front bench over claiming travel expenses to buy a house on the Gold Coast.

Speaker Bronwyn Bishop lasted 18 days before her inevitable resignation over taking a helicopter to a Liberal fundraiser.

How many more days will Joyce last?

For about 24 hours in the middle of the week, Joyce and coalition MPs thought he had pulled out of the death spiral.

The flood of revelations about his affair with staffer Vikki Campion had seemingly dried up.

The 20 other Nationals MPs lined up behind their leader, after some grumbling from a small group.

They see him as an electoral asset, a man who bombastically stands up for the regions, delivering money and votes.

Liberal MPs privately said they thought this scandal was going to end with a resignation until Joyce appeared to pull it out of the fire on Wednesday.

Despite his mistakes, one MP summed up his worth to the coalition:

"We're better with him than without him."

Then the pressure ratcheted up.

Prime Minister Malcolm Turnbull told parliament Joyce would be taking personal leave next week instead of being acting prime minister while Turnbull was in Washington.

More questions were raised about a rent-free townhouse Joyce was given to live in for six months, thanks to his rich friend Greg Maguire.

Then there were questions about a function his department paid for at Maguire's Armidale hotel.

And it was revealed Joyce's push to move the Australian Pesticides and Veterinary Medicines Authority to Armidale meant taxpayers have spent almost $15,000 putting staff in that same hotel.

Turnbull had just spent nine days defending Joyce, in parliament, to journalists, to anyone.

But as each latest revelation came out, the prime minister had to ask himself why he was defending the increasingly indefensible.

A passionate and strident Turnbull waited until 4.55pm on Thursday to unload.

The PM said Joyce humiliated his wife, daughters and new partner, in making a "shocking error of judgment".

Turnbull told Joyce to consider his position on his week off and when asked if the Nationals leader should resign, he offered this: "Barnaby is the leader of the National party, okay? They are our coalition partners. They have a coalition agreement."

The message was extremely clear.

Quit, Barnaby, quit.

Instead of heeding that call, Joyce returned fire on Turnbull's comments.

"I believe they were in many instances inept, and most definitely in many instances unnecessary,' he said.

He refused to resign, and said there is nothing worse for the Nationals than someone trying to interfere in their internal party affairs.

Turnbull can't sack Joyce because he's the leader of the Nationals, and only the Nats can choose their boss.

The Nationals were originally banking on voters feeling the humanity of a no-win situation.

Admittedly Joyce did have a tough choice - to leave his wife of 24 years for his pregnant girlfriend, or stay at home and put her out on the street?

Either story is a bad look, although Joyce should be criticised for refusing multiple media offers to confirm the pregnancy and get out in front of the issue.

But the scandal has created a rift and it is not clear the relationship can be repaired.

Joyce is stubbornly clinging to his leadership, Turnbull is unlikely to make an apology, and the Nationals are so far backing their man to the hilt.

Something has to give - or the scandal will drag on and on.

Australian Associated Press