OTTAWA -- The Speaker of Canada's Senate, Pierre Claude Nolin, has died, leaving the much-maligned institution without a leader in the midst of its greatest crisis.

A spokeswoman for the Senate says Nolin died just after 7 p.m. Thursday. The 64-year-old, appointed to the Senate in 1993 by Brian Mulroney, had been battling a rare cancer since 2010.

He became Speaker just last November, the unanimous choice of Conservative, Liberal and independent senators who saw him as a smart, respected, independent-minded man who could steer the upper house through the final dramatic chapters of the expenses scandal that has rocked the Senate to its foundations.

His death comes in the midst of the trial of disgraced Senator Mike Duffy for allegedly filing fraudulent living and travel expense claims. The trials of two other senators, Patrick Brazeau and Mac Harb, on similar charges are set to start within months and the RCMP continue to investigate a fourth, Pamela Wallin.

The auditor general, meanwhile, is finishing up an unprecedented audit of all senators' expenses and is expected to report his findings in June.

When he took over the Speaker's chair, Nolin signalled his intention conduct himself in a non-partisan manner and to devote himself to defending and restoring the reputation of the tarnished upper house.

As Speaker, Nolin was also chair of the Senate's internal economy committee, which establishes the rules for how senators can spend taxpayers' dollars and claim reimbursement for expenses.

In his last public comments earlier this week even as he was battling illness, Nolin vowed to tighten those rules and make senators more accountable for the money they spend.

"Under my leadership as Speaker, the Senate is committed to modernizing its rules and processes in keeping with best practice standards," Nolin said in a statement issued Monday to The Canadian Press.

"We are moving towards greater transparency and accountability, principles upon which I strongly believe. To this end, we will be updating our requirements around Senator office budget reporting to include publishing a more detailed breakdown of expenses.

"We will continue the work of modernizing and updating Senate rules and policies, taking into consideration the findings of the Auditor General's upcoming report on Senate expenses."

Although he was a loyal Conservative, who cut his teeth as an organizer for Mulroney in Quebec, Nolin had an independent streak. He voted against his party on a number of occasions and spoke out against Prime Minister Stephen Harper's doomed initiative to turn the appointed upper house into an elected chamber.

Nolin also bucked the Tory tide in 2002 when he chaired a special Senate committee that recommended legalization of marijuana.