A senior Nationals senator is unsure if Barnaby Joyce will lead the party to the next federal election following his extramarital affair.
Asked if the deputy prime minister was the best person to lead the Nationals to the poll, John Williams told ABC radio on Monday: "He's certainly been a great leader and I stick by that."
But later he told ABC TV: "Let's see how all of the travel things come out and so on. I just don't know.
"I don't know if he's done anything wrong by the law of the parliament or the taxpayers and I can't judge on that."
Mr Joyce's relationship with his now pregnant former staffer Vikki Campion, 33, was publicly confirmed last week just two months after he told parliament his 24-year marriage was over.
Senator Williams lamented the recent headlines about his leader's personal situation.
"He's under a lot of pressure and he's been a good mate for many years. I wish I could turn the clock back, but I can't," he said.
Questions are now being asked about Ms Campion's employment during her time with the federal Nationals, after the media advisor last year moved from Mr Joyce's office to the office of minister Matt Canavan and later to the office of Nationals whip Damian Drum.
Deputy Labor leader Tanya Plibersek has called on the coalition to be transparent about her job trajectory after the relationship with Mr Joyce became known within government circles last year.
"The only area in which there is a genuine public interest is in the area of the expenditure of taxpayers' funds," Ms Plibersek said on Sunday.
"There have been questions over the last couple of days about jobs that have been created for Vikki Campion, the expenditure of taxpayer funds on travel."
The government maintains nothing untoward happened, pointing to Ms Campion's strong job skills.
"There are lots of whispers being mounted, it seems, but very few real substantiated allegations that I've seen being made," cabinet minister Simon Birmingham told Sky News.
Ms Campion, a former journalist, was initially a media advisor for Mr Joyce before going to work for Senator Canavan.
When Senator Canavan stepped down from the front bench in July following question over his citizenship, she when to work for Mr Drum.
