Liberal senator Stephen Parry has confirmed he is a British citizen and will now resign from the Parliament.

Key points: British Home Office confirmed Parry has citizenship through his father

British Home Office confirmed Parry has citizenship through his father He will submit his resignation as a Tasmanian senator and Senate President tomorrow

He will submit his resignation as a Tasmanian senator and Senate President tomorrow Richard Colbeck will most likely get his Senate seat, but it's not yet clear who would become President

Yesterday, Senator Parry revealed he had doubts about his citizenship status because his father was born in the UK, and emigrated to Australia in the 1950s.

He has now released a statement saying the British Home Office confirmed he is a citizen by virtue of his father's birthplace.

In a letter to his Senate colleagues, he wrote it was "with a heavy heart" he had to inform them he would be submitting his resignation as Senate President and as a Tasmanian senator to the Governor-General tomorrow.

The timing of Senator Parry's announcement means he will not be able to make a farewell speech in the Upper House, but he thanked his colleagues in his statement for their support and confidence in him.

He said he regarded many of his colleagues as good friends, "from all quarters of the chamber".

Senator Parry's revelation came just four days after the High Court kicked five politicians out of Parliament for breaching the constitution's dual citizenship ban.

He was widely criticised by the Federal Opposition for holding back on announcing his citizenship concerns.

The Opposition demanded he stand down as Senate President but his Liberal colleagues defended him, arguing he was waiting for clarity about the interpretation of the constitution from the High Court.

ABC election analyst Antony Green argued the 45th Parliament had thrown up more disqualifications than ever before.

"There shouldn't be so many candidates disqualified," Mr Green said.

"Until this term of parliament, we'd only ever had two of these [recounts] done — Robert Woods [1988] and Heather Hill [1999]."

Liberal senators pay tribute to 'stellar' Parry

Fellow Tasmanian Liberal senator Eric Abetz released a statement to say he was "deeply disappointed" in the news.

"Stephen has not only been a valued colleague but has been an exceptional President of the Senate and chief whip before that," Senator Abetz said.

"While this is a disappointing turn, Stephen can find comfort in his stellar list of achievements for the people of Tasmania and for the Parliament."

Senator Abetz also said it was likely former Liberal senator Richard Colbeck would replace Senator Parry, and said he was confident he would "hit the ground running".

Mr Colbeck was bumped down the Tasmanian Liberal Senate ticket in a factional dispute ahead of the last election.

Tasmanian Liberal senator Jonathon Duniam said Senator Parry would be missed.

"I'm terribly upset for Stephen and his family, but also for the fact that he won't be contributing as a servant of the state of Tasmania," Senator Duniam told the ABC.

"I also look forward to working with Richard Colbeck should he return to the Senate after the vacancy is dealt with."

Attention turns to who will replace Parry as President

Labor senators are privately disappointed Senator Parry will no longer be president.

While he is their political opponent, he is generally regarded by Opposition senators as balanced and thoughtful.

The Coalition will choose his replacement as senate president from the ranks of those who nominate.

Some have suggested Nationals senator John Williams could take on the job, instead of another Liberal.

But it is almost certain Senator Parry will be replaced in the senior position by a fellow Liberal.

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