Soon-to-be-senator Peter Georgiou has been in a Perth hospital for four days, struck down with a virus.
The electrical contractor has officially replaced his brother-in-law Rodney Culleton as One Nation's WA senator, appointed by the High Court on Friday, after a recount of the ballot papers named him as the next electable candidate.
But he'll be celebrating from his bed at the Royal Perth Hospital, where he has been for four days suffering a virus, his father Dimitrios Georgiou told AAP.
His father says it's unclear when Peter will be able to leave hospital, but is hopeful it will be within a few days.
Mr Georgiou could be sworn-in as a senator as early as March 20, when the Senate returns from its month-long break.
It follows a dramatic end to his brother-in-law's short-lived political career, with Mr Culleton removed from parliament in January after the Federal Court declared him bankrupt.
His election was also ruled invalid by the High Court in February because he had been convicted of larceny at the time, even though the conviction was later annulled.
Mr Georgiou's father says he's happy for his son, but concedes he didn't want him to embark on a career in politics.
"He's a very good person and a good businessman," he told AAP.
"It's up to him what he wants to do, he's been elected."
Mr Culleton tried to have Friday's proceedings adjourned and provided a list of 10 reasons why it should be delayed.
But the court found none of the reasons were relevant and refused the request.
One Nation leader Pauline Hanson said in December that she was "glad to see the back of him" after Mr Culleton quit the party, describing him as a pain in her backside.
Senator Hanson on Friday said Mr Georgiou was a "lovely guy".
"He has a lot of respect for me, he's loyal to me," she told Nova 93.7.
A spokesman for Senator Hanson said she would be visiting him in hospital later on Friday afternoon.
He said Mr Georgiou was expected to be fit for parliament when it resumes later this month.
A spokeswoman for the hospital said he was in a stable condition.
The High Court will need to inform Senate Clerk Richard Pye of the decision in writing, and the new senator can be sworn in once the document is tabled in parliament.
