On Tuesday afternoon President of the Senate, Stephen Parry, took his own colleagues by surprise when he revealed advice on his own citizenship had been sought.

Senator Parry’s late father was born in the United Kingdom. 

After Friday’s High Court ruling that five politicians were ineligible to be elected, Senator Parry wrote to the British Home Office “seeking clarity as to the status of my citizenship with the United Kingdom”.

In a statement, Senator Parry revealed he would resign if he was found to have breached the Constitution by holding British citizenship.

“I would further resign as a Senator for the State of Tasmania and not await the outcome of any referral to the High Court, as I believe the High Court has made it abundantly clear what action is required,” he said.

Senator Parry would become the first Liberal to be forced out of Parliament in the citizenship fiasco.

His resignation would catapult former North-West Coast Senator, Richard Colbeck, back into parliament.

Mr Colbeck has spoken with the executive of the Tasmanian Liberal Party and confirmed he is interested in filling any vacancy.

While eager not to “get too ahead of things”, Mr Colbeck said he had already checked he was eligible to serve.

“I spoke to my mum and dad, they were both born in Australia and all of their parents were born in Australia,” he said. 

Since leaving office last year, Mr Colbeck has made no secret of his desire to return to politics.

“I wasn't ready to leave, there were things I was in the middle of doing,” he said. 

“I still think I've got something to offer, there are things I've still been working on.”

While Senator Parry waits for advice, Mr Colbeck said he would remain reserved. 

“I suppose I’ll keep on doing what I've been doing until I know definitively if my circumstances are going to be changed, weed the garden and continue the work I've been doing,” he said.

Political analyst Kevin Bonham said, due to the flow of preferences, modelling showed Australian Greens Senator Nick McKim would also be unseated in favour of Pauline Hanson’s One Nation.

The bombshell by Senator Parry comes several days after the High Court ruled that Deputy Prime Minister Barnaby Joyce, and four senators, were invalidly elected because they were dual citizens.

Senator Parry – elected in 2004 – is the first Tasmanian to be embroiled in the crisis.

In his maiden speech, Stephen Parry spoke about his Australian family history.

"I am a Tasmanian by birth and come from a line of many generations of Tasmanians,” he said in 2005. 

“In fact, I am a descendant of the First Fleet convicts who arrived on 26 January 1788 onboard the ships.”

Labor Senator Helen Polley was elected at the same time as Senator Parry and was “stunned” by his news. 

Senator Parry’s colleague, Eric Abetz, was “shocked” and said his “departure would be a huge loss”.

“I am hopeful that any advice from the United Kingdom will allow him to remain in the Senate,” he said.

Mr Bonham predicted the loss of a Liberal member would be devastating for the party’s standing.

He said questions would be asked about who was candidates’ vetting – but Malcolm Turnbull would welcome the return of the former Tourism Minister.

“The Prime Minister will probably be glad to have Colbeck back on board – he was considered to be supportive compared to Abetz,” he said.