Prime Minister Justin Trudeau's pick to fill a vacant Senate seat from Manitoba has turned down the job, CBC News has learned.

Harvey Chochinov, a professor of psychiatry at the University of Manitoba, and a leading researcher on palliative care, was recommended for a seat in the Red Chamber by the prime minister's arms-length appointments advisory board last fall. The Winnipeg doctor was one of 145 Manitobans who applied to fill three vacancies from the prairie province.

"Due to personal, family and professional reasons, Dr. Harvey Max Chochinov has advised the Prime Minister that, regrettably, he is unable to accept the proposed appointment to the vacant Senate position for Manitoba," a spokesperson for the Privy Council Office, the department that serves the prime minister, said in an emailed statement.

While the eight other people appointed at the same time took their seats late last year, Chochinov was never actually sworn-in.

The Senate's website still lists a vacancy from Manitoba.

"An announcement regarding the current Senate vacancy for Manitoba ‎will be made in due course," the spokesperson said, while adding Chochinov would not be made available for an interview.

There are currently five vacancies after the recent retirements of Liberal Senators Jim Cowan and Willie Moore, Conservative Senator Nancy Ruth and Independent Senator John Wallace.

Opposes doctor-assisted dying

Chochinov told CBC News last October that he was "honoured to be considered" for the Red Chamber, and said he was looking forward to serving Manitobans in Ottawa.

Former prime minister Stephen Harper tapped Chochinov to help his government respond to the Supreme Court's Carter decision, which paved the way for the legalization of doctor-assisted death.

Chochinov has been a vocal opponent of legalizing assisted dying.

He is the director of the Manitoba Palliative Care Research Unit at CancerCare Manitoba. He holds the Canada Research Chair in Palliative Care, among other roles.

"My expectation is that while I will obviously have to rearrange my schedule and there'll be some juggling to do, my hope is that the work will continue on, that I'll continue to have a hand in the ongoing research," he said last fall at the time of his appointment.