The Nationals are already making preparations in case the High Court orders a byelection, with campaign booth 'captains' contacted and rosters being prepared for volunteers to work on pre-poll stations.

The High Court this week held three days of hearings on whether the so-called "citizenship seven" - Mr Joyce and six senators - were validly elected in accordance with section 44 of the constitution, which prevents dual nationals from serving in Parliament. Mr Joyce discovered in August he was a New Zealand citizen by descent.

Chief justice Susan Kiefel has said the bench will endeavour to deliver rulings "as soon as possible".

The Turnbull government has a one seat majority in the House of Representatives and is sweating on the ruling in Mr Joyce's case; Labor has said it will not provide a 'paired' vote in the event Mr Joyce has to re-contest his seat.

This would see the government temporarily reduced to 75 seats in the 150 member chamber, giving Labor a chance to destabilise the government and potentially force passage of a banking royal commission and reverse to cuts to penalty rates.

Nationals operatives in Mr Joyce's northern NSW seat of New England told Fairfax Media on Friday there was a growing expectation a byelection will be ordered - despite repeated assurances from Prime Minister Malcolm Turnbull, based on advice from the Solicitor-General, the government was confident Mr Joyce would not be ruled ineligible.

The expectation on the ground is that Mr Joyce will win any snap poll and potentially increase his primary vote from an already high 52.3 per cent.

"People have the shits about this," a Nationals operative said. "Barnaby was born here and we voted for him. There are more important issues to worry about. I wouldn't be surprised if increases his margin."

Mr Joyce told the Northern Daily Leader on Friday he was enduring "an anxious wait, it would be ridiculous to say anything else".

"I'm hoping the decision either way is made as quickly as possible, so we know exactly what we're off to next," he said.

"If it goes against us, we go to a byelection straight away. If it goes with us, we just get back to work."

Mr Joyce said he was prepared to face voters again "but we won't get ahead of ourselves, we'll stay humble and let people make up their own mind."

Labor senator Sam Dastyari has said his party would stand a candidate in any byelection, though the ALP typically does not poll well in the conservative seat.

Mr Windsor, a bitter rival of Mr Joyce who previously held the seat and has joined the High Court fight against the Deputy Prime Minister, is also a chance to stand. He has declined to reveal his intentions.

A One Nation spokesman said the party had not selected a candidate but had strong support in the area and would likely enter the contest.

"People feel let down by the Nationals, so there are a lot of calls from locals for us to run, and we have to give that consideration once the High Court makes it ruling," the spokesman said.

In the unlikely event One Nation won the seat, the party would achieve official party status for the first time, which would ensure more resources and staff.

Similarly, NSW Shooters, Fishers and Farmers MP Robert Borsak told Fairfax Media: "We are certainly considering it [standing a candidate], if we can find the right candidate we will".

The minor party hopes to win state seats at byelections in southern NSW this weekend.