Joyce, who holds the rural New South Wales electorate of New England, has been an outspoken member of Parliament since 2005 and was elected leader of the National Party, and therefore deputy prime minister, in 2016.
"All complaints are taken seriously and treated with the strict confidentiality and given due process", National Party federal director Ben Hindmarsh said in a statement.
After leaving his wife of 24 years and mother of his four daughters, Natalie Joyce, he and Ms Campion now live rent-free in an apartment owned by a wealthy political donor.
The woman who accused Joyce has not been identified.
As pressure on his position grew, he did press interviews in which he blamed public life for the breakdown of his marriage.
In response to the scandal, the prime minister announced a ban on government ministers having sex with their employees and later called Joyce's actions a "shocking error of judgement".
PRIME Minister Malcolm Turnbull has refused to offer his support to his deputy, Barnaby Joyce, as the fallout from his extramarital affair worsens. He subsequently renounced his New Zealand citizenship and convincingly won a December by-election to return to the No. 2 post in the Cabinet.
During the election campaign, despite eventually enjoying a positive swing, he faced a number of security alerts and media speculation about his personal life.
Confidant of PM turns state witness
So far, partners in his governing coalition have stood by Netanyahu, saying they were awaiting the attorney-general's next moves. The new bribery case was one of two revealed on Tuesday involving the same former spokesman, a close Netanyahu confidant.
The favourite to replace Joyce as leader is Michael McCormack, a junior minister from New South Wales. "I've asked for the right of the person who's made the allegation and I've asked for my right of defense that be referred to the police".
Australian Twitter users have been making fun of Barnaby Joyce, particularly his role in the "War On Terrier", after he announced he will resign as the country's deputy prime minister.
Mr. Joyce, through a spokesman, denied those allegations. "I believe they were in many instances inept".
Barnaby Joyce's announcement of his resignation from the Nationals leadership made headlines around the country this afternoon - but a freakish phrase used in his speech has stolen his spotlight.
"It's got to stop".
Speaking to reporters in Washington, D.C. ahead of his meeting with US President Donald Trump, the Prime Minister countered the idea that he needed to "soothe" any wounds over the matter.
This was the question people turned to social media to answer as Barnaby Joyce began his resignation speech this afternoon.
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