Prime Minister Malcolm Turnbull has named Foreign Minister Julie Bishop as Acting Prime Minister during his trip to Israel.
"I will be travelling oversees to Israel on Monday to participate in the commemoration of the battle of Bersheva ... it was one of the most dramatic victories undertaken by Australia in the First World War," Turnbull told reporters in Sydney.
"Julie Bishop will be acting Prime Minister while I will be overseas."
Turnbull said Barnaby Joyce remained the leader of the federal Nationals but could no longer fulfill the Acting Prime Minister role because he was "not currently in the parliament".
"Therefore the normal order of precedence in terms of acting Prime Minister falls to Julie Bishop as deputy leader of the Liberal Party and Foreign Minister," Turnbull said.
The reshuffle comes after The High Court on Friday ruled Joyce, Fiona Nash, Malcolm Roberts, Scott Ludlam and Larissa Waters as ineligible to sit in parliament on citizenship grounds.
The court ruled that Matt Canavan and Nick Xenophon did not fall foul of dual-citizenship laws.
Joyce now faces a by-election in his northern NSW seat of New England on December 2.
In the wake of the ruling on Joyce there were reportedly talks about whether Bishop would step up as acting PM, or if the role would go to senior National Nigel Scullion.
Turnbull said the "interim measures" would not involve swearing in a new deputy Prime Minister.
"There will be no Deputy Prime Minister sworn in," he said.
"We've agreed in these special interim circumstances, Julie will be acting PM while I'm away."
More to come.