Using a giant inflatable likeness of Sen. Mike Duffy to represent largesse and wasteful spending in the upper chamber, the Canadian Taxpayers Federation called Thursday for a national referendum to determine the future of the Senate.

The 31-foot-tall inflatable mascot was dressed in a blue suit and red tie, with one hand outstretched and the other holding a briefcase bursting with cash.

"Its 2,150 cubic feet of hot air," Gregory Thomas, federal director of the Canadian Taxpayers Federation, told CTV News Channel. "We think that's highly symbolic of Canada's Senate and obviously he's clutching a bag of money about the size of a Volkswagen."

The CTF is calling for a referendum to be held during the next federal election in 2015, and plans to take the giant inflatable on a campaign to promote the call this summer.

The Senate has been under close scrutiny in recent months over the spending habits and expense claims filed by several senators, including Duffy, who repaid $90,000 in improperly filed expenses with a personal cheque from Prime Minister Stephen Harper's former chief of staff, Nigel Wright.

Thomas suggested the Senate is a relic from the past, and said it's time to ask Canadians whether they want it anymore.

"You've currently got Senators under investigation by the RCMP for allegedly filling their pockets with taxpayers' cash. You've got unelected Senators gutting legislation passed by the democratically elected House. And until Harper finally appointed enough Conservatives to form a majority, you had unelected opposition Senators blocking the elected government's legislation," he said.

"It's outrageous, in the 21st century, that unelected Senators are able to get away with these things."

Thomas said a recent survey of CTF supporters showed sentiment had changed. In the past, the organization has taken the position that there were two options for the Senate: "elect or abolish."

But in a recent poll of over 7,000 supporters, 65 per cent said they favoured getting rid of the body altogether, while 82 per cent supported the idea of a national referendum on the subject.