Pat Martin, a New Democrat MP from Winnipeg, is particularly incensed that Senator Don Plett is serving as the campaign co-chair and a leading spokesman for the provincial Progressive Conservatives leading up to Manitoba's Oct. 4 election.
"Senators should mind their own business, or they should be paid for by the party that they're representing, not by the Canadian taxpayer," Martin said at a news conference on Parliament Hill.
Plett, former president of the federal Conservative party, was appointed to the upper chamber and its $132,000 annual salary by Prime Minister Harper two years ago.
Plett says he's a taxpaying Manitoban and has every right to volunteer his time to a provincial political cause in whatever capacity he can.
"Let's be perfectly clear: If you're a Conservative, you're a Conservative I think both provincially and federally," Plett said in an interview. "Will you have overlap? Absolutely you will."
But Plett maintains he's continuing his Senate work and has "every intention of being in my seat in the Senate chamber on Sept. 27 when we resume."
Plett added he'll formally take off two days from his Senate duties to deal with Manitoba's voting day in October, which he is entitled to do.
With three provincial elections currently underway and an increasingly active Conservative upper chamber, Martin is just the latest critic to raise questions about partisan activity by senators.
Last fall, Liberal MPs complained that Conservative Senators — including Plett — were distributing taxpayer-funded partisan flyers in opposition-held ridings.
Tory Senator Bob Runciman told the Toronto Star "the Conservative campaign folks" asked him to send the flyers.
Martin said Friday that with more than 50 Conservative senators each costing taxpayers $500,000 a year in salary, staff and travel, it amounts to a $25-million annual subsidy to the party — "if they continue to engage in this unapologetic, overt, partisan politics rather the doing the job they're supposed to do."
Harper promised during the spring federal election campaign to phase out the $2.04 per-vote subsidy that has funded federal parties for a decade, costing the federal treasury about $27 million in 2009.
But the prime minister has been packing the Senate with partisans who continue party work.
Doug Finley, Harper's longtime campaign general, was appointed to the Senate with Plett in 2009, along with Irving Gerstein, the architect of the party's superbly successful fundraising machine and Carolyn Stewart-Olsen, Harper's former press secretary.
"We have (former broadcaster) Senator Mike Duffy galivanting around the country as a full-time political fundraiser for the Conservative party, for god's sake, unapologetically," said Martin.
Last week in Ottawa, Foreign Affairs Minister John Baird and Duffy attended a high-profile campaign event for a provincial Tory candidate in Ontario's Oct. 6 election.
Plett said the issue is not new, not particular to Conservatives, and doesn't break any rules.
"How do you tell volunteers you can work provincially, you can't work federally? Where do you draw the line?" asked the former longtime national party president.
"MPs are also taxpayers here in our province. What right do they have to go and support somebody? I think they should have that right."