It should only take about one hour for voters to find out who will replace four senators disqualified over dual citizenship, when a recount is held on Monday.

Key points: New make-up of the Senate to be known early next week after recount

New make-up of the Senate to be known early next week after recount Former Nationals deputy leader Fiona Nash set to be replaced by a Liberal

Former Nationals deputy leader Fiona Nash set to be replaced by a Liberal PM again rebuffs calls for an audit of the citizenship of all politicians

After months of uncertainty, last week Greens senators Scott Ludlam and Larissa Waters, Nationals senator Fiona Nash and One Nation senator Malcolm Roberts were all found to have been invalidly elected because they held dual citizenship.

The High Court issued an order today for the Australian Electoral Commission (AEC) to conduct the recount.

The AEC will start the count on Monday, with the actual process taking about an hour.

The court heard time was needed to give scrutineers notice to attend.

The AEC will file the results to the court next week, with a list of final orders to be issued on Friday, endorsing the replacement senators.

National Party to lose a seat

The most likely outcome is that disqualified senators will be replaced by the next candidate on each party or coalition ticket.

In New South Wales the Liberals and Nationals share a joint senate ticket, meaning the former Nationals deputy leader Fiona Nash is likely to be replaced by a Liberal candidate.

The next person in line is disability advocate Hollie Hughes. She is expected to take up the opportunity, meaning The Nationals party-room will shrink by one member.

The most senior member of the Nationals caught out in the citizenship crisis, Barnaby Joyce, is recontesting his seat of New England in a by-election.

His situation is different because he is in the Lower House.

The citizenship debacle also claimed the scalp of Liberal senator Stephen Parry, who did not reveal concerns about his own potential dual citizenship until after the High Court rulings on the original senators and Mr Joyce.

He has since resigned after the UK Home Office confirmed he was a British citizen by descent.

Turnbull again rejects audit call

Attention has again swung to the potential for further federal politicians to be sitting in parliament in violation of the dual citizenship provisions.

The Greens and senate crossbencher Cory Bernardi have been pushing for a comprehensive audit of all members of parliament, forcing them to present documents to prove their heritage.

The major parties have previously shut down the idea of an audit, but some backbenchers within Labor and the Coalition are open to the prospect.

Speaking from Israel the Prime Minister indicated he was not willing to reconsider his position.

"The fact is every member and every senator has a personal responsibility and an obligation to comply with the constitution," he told reporters.

Treasurer, Scott Morrison, mocked the proposal suggesting it was not the job of government to back a wide-spread investigation.

"It isn't to run some sort of reality television show of Who Do You Think You Are," he said.