Conservative Senator Bob Runciman is calling on Ontario Premier Kathleen Wynne to take a lead on Senate reform at next month's Council of the Federation meeting of premiers.

The Ontario senator sent an open letter to Wynne Thursday afternoon highlighting the "added urgency" following this week's scathing auditor general's report that found 30 former or current senators filed nearly $1 million in questionable expense claims over a two-year period.

The Supreme Court shot down the federal government's plan for Senate reform last year but provided a roadmap on how to move forward: namely, through the provinces. Changes, such as requiring provincial elections for Senate candidates or fixed terms for senators, would require approval of at least seven provinces that represent at least half the population, the top court ruled.

Runciman noted that individual provinces can initiate change by passing a constitutional amendment in their legislature. That would trigger a three-year window to recruit six other provinces (representing at least 50 per cent of the population) to pass the same legislation.

"You have previously acknowledged your support for reform and Ontario has a long history of putting Canada first," he wrote to Wynne.

"With your leadership, Ontario could again lead the way on bringing much needed democratic legitimacy to a body that Canadians overwhelmingly want to see reformed."

Deputy Premier Deb Mathews responded to the letter Thursday afternoon, saying the Senate can introduce its own legislation for reform based on the auditor general's report. She added that the province would be willing to participate in talks about Senate reform, but seemed unwilling to lead.

"Ontario is ready to participate if the federal government decides to lead collaborative pan-Canadian discussions about Senate reform," the letter said.

A spokesperson in Wynne's office delivered the same line on Wednesday, before Runciman's letter,