Australia's deputy prime minister quit the Cabinet on Friday over allegations that he sexually harassed a woman.
Barnaby Joyce quit his ministerial role but said he would not resign from Parliament, ensuring that Prime Minister Malcolm Turnbull maintains his single-seat majority in the House of Representatives.
The allegation of sexual harassment adds to the scrutiny he has faced since it was revealed earlier this month that he and his former media secretary, Vikki Campion, are expecting a baby in April.
Questions have been raised about her employment in two government jobs after and the rent-free apartment owned by a wealthy political donor where Mr Joyce and Ms Campion now live.
Mr Joyce said his Nationals party, the junior party in the ruling coalition, will pick a new leader - who will become deputy PM - on Monday.
"It's incredibly important that there be a circuit-breaker, not just for the Parliament, but more importantly, a circuit-breaker for Vikki, for my unborn child, my daughters and for Nat," he told reporters, referring to his estranged wife of 24 years and mother of his four daughters, Natalie Joyce.
He has also denied a media report that he pinched a woman's bottom while drunk in a Canberra pub several years ago.
He said media reports that an unidentified woman had made a sexual harassment complaint against him was the "straw that breaks the camel's back".
He denied the allegations, and said he requested they be referred to police for investigation.
Mr Joyce, who has led his party since elections in mid-2016, said he would not accept any ministerial portfolio.
As well as deputy prime minister, he was minister for infrastructure and transport.
Nationals president Larry Anthony, the party's senior bureaucrat, said in a statement: "The party will greet this news with a heavy heart but we understand and respect his decision to stand down as leader."
Mr Turnbull said in a statement that the coalition government "partnership is undiminished" by the Nationals' leadership change.
The prime minister and his deputy have openly attacked each other since news of Mr Joyce's affair became public.
Mr Turnbull accused Mr Joyce of making a "shocking error of judgment".
Mr Joyce described his leader's remarks as "inept" and "completely unnecessary".
In a move interpreted by some as punishing his deputy for a politically damaging scandal, Mr Turnbull did not appoint Mr Joyce to the role of acting prime minister during his Washington visit this week.