Deputy Prime Minister Barnaby Joyce has described his citizenship case as being forced on him by "malicious fate" and accused others of using it to "open wounds and play a very poor game".

Key points: Barnaby Joyce is the only Lower House MP caught up in the crisis

Barnaby Joyce is the only Lower House MP caught up in the crisis If High Court rules against him, Mr Joyce says he'll go to a by-election

If High Court rules against him, Mr Joyce says he'll go to a by-election Tony Windsor has not said whether he would contest a by-election

Mr Joyce is among the Citizenship Seven waiting for the High Court to decide whether their dual citizenship makes them ineligible for Parliament.

The Nationals leader and Member for the New South Wales seat of New England is the only Lower House MP caught up in the crisis, and if the court rules against him he says he will go to a by-election.

The Turnbull Government only holds a one-seat Lower House majority. The Nationals are confident of retaining the seat but some party insiders expect it would be a hard-fought and potentially "dirty tactics" campaign.

Mr Joyce kept a low profile throughout last week's three-day court hearings, but on Saturday he wrote an opinion piece for Tamworth's Northern Daily Leader, the main newspaper in his electorate.

"I never wanted this, it was forced on me by malicious fate and others have used this to open wounds and play a very poor game."

Commenting on the political climate in the nation's capital he went on to criticise the "crazy boarding school" of Canberra.

"They revel in the salacious at the expense of the people who we should be totally, and only, focused on," he wrote.

Mr Joyce suggested the High Court could hand down its decision at the end of the coming week. The uncertainty would overshadow this week's parliamentary sittings.

"I hope for the best but prepare for the worst", the Deputy Prime Minister wrote.

State of play in New England

Nationals internal polling in New England, conducted towards the end of last week, had Mr Joyce increasing his grip on the seat.

Former independent member for New England Tony Windsor, who joined the High Court action against Mr Joyce, is considered the most serious threat but has not said whether he would contest a by-election.

Mr Windsor ran against Mr Joyce in last year's federal election and was convincingly beaten.

There is deep personal enmity between the pair, which played out publicly in the 2016 campaign. Mr Windsor has recently taunted his successor with personal criticism.

The ABC has been told The Nationals poll reached over 1,000 voters, with about a 3 per cent margin of error, and found support for Mr Windsor had softened since last year's federal poll.

Former MP Tony Windsor has not confirmed whether he would run a by-election for New England. ( ABC News: Tom Hancock )

The field of candidates in a by-election scenario is expected to be wide.

Labor's Sam Dastyari has confirmed the opposition would run a candidate, and "run to win".

The Greens are also expected to field a contender.

One Nation and the Shooters, Fishers and Farmers party are also leaving the door open to running candidates.

The Nationals faced a strong contest from the Shooters, Fishers and Farmers Party in New South Wales state by-elections in the seats of Murray and Cootamundra on Saturday.

The Nationals federal party will be closely watching the results to measure sentiment across the state.

Mr Joyce's office has confirmed he is spending this weekend in his electorate.

Joyce argues he never knew he was a Kiwi

The Deputy Prime Minister and Nationals leader stunned Parliament earlier this year when he revealed he was a New Zealand citizen by descent, because his father was born across the Tasman.

Bret Walker SC represented Barnaby Joyce during the Citizenship Seven hearings, arguing he never knew he was a Kiwi. ( ABC News: Matt Roberts )

During the court hearings, his lawyer Bret Walker SC suggested Mr Joyce could never have known his father's heritage could also make him a dual citizen.

It was a position shared by the Commonwealth, who were effectively arguing that Mr Joyce, deputy Nationals leader Fiona Nash, former minister Matt Canavan and crossbench senator Nick Xenophon should not have their elections ruled invalid.

But Tony Windsor's legal team, led by the former solicitor-general Justin Gleeson, argued ignorance was not a defence and that Mr Joyce should be turfed out.