Just 13 per cent of Canadians believe Prime Minister Stephen Harper is telling the truth when he says he had no knowledge of Nigel Wright’s $90,000-bailout of Sen. Mike Duffy, according to a new poll.

The CTV News Ipsos Reid poll also found that 44 per cent were “not sure whether or not the prime minister had any knowledge of the monetary gift made by Mr. Wright at the time,” and 42 per cent said they are “convinced that the prime minister would have known about the monetary gift by Mr. Wright at the time.”

In a sign of how politically damaging the scandal could be, the survey also found that 66 per cent of respondents considered the involvement of the Prime Minister’s Office a “serious ethical breach.”

The remaining 34 per cent said it “represents a relatively minor issue that says little about the ethical fitness of the Prime Minister and his government’s fitness to govern Canada.”

The poll was conducted on May 27 and 28 and included an online panel of 1,009 respondents. The results are considered accurate within +/- 3.5 percentage points.

When asked what should happen to senators who were found to have violated expense policies, 23 per cent said it’s possible that they made “clerical mistakes” and should be allowed to pay back ineligible expenses and remain a senator. However, 77 per cent said no matter their “personal excuses,” if they are found to have breached expense policies, they “should resign from the Senate.”

A whopping 92 per cent of respondents either strongly or somewhat support requiring senators and MPs to post expense reports, with receipts, online.

Meanwhile, when asked about the fate of the Senate:

43 per cent said it should “be done away with completely,” up seven points from February.

45 per cent said it should “be reformed to make it, for example, an elected body,” up three points.

13 per cent said the senate should be “kept as is,” down nine points.

RCMP investigation

The vast majority of Canadians want either an RCMP investigation or a public inquiry into the ongoing Senate expense scandal, and felt that senators should not be left to handle the probe themselves.

The survey found that 44 per cent of respondents think the RCMP should lead an investigation, while 31 per cent called for a public inquiry led by a judge.

Only 6 per cent said the Senate itself should lead an investigation, while 12 per cent said the House of Commons Ethics Committee should be tasked with the job.

One in 10 respondents said they believe the issue should be dropped and no investigation should be carried out “because it is not really a big deal.”

The Senate’s internal economy committee revisited the issue of senators’ expense claims amid ongoing questions about sanitized audit reports, expenses billing, and what Harper knew of a $90,000 cheque his chief of staff wrote to help Sen. Mike Duffy repay ineligible expenses.

The cheque is also the subject of an investigation by Canada’s Ethics Commissioner, Mary Dawson. The RCMP has also requested a number of documents in connection with Senate expense claims.

The opposition has hammered the prime minister about the expense scandal during question period in the House of Commons this week, trying to determine what Harper knew and when he knew it.

Harper insists he knew nothing of the cheque until Wright informed him about it on the morning of May 15. Duffy repaid the ineligible expenses in March.

Liberal Leader Justin Trudeau used his time in question period Wednesday -- much as he did the day before -- to question the timeline of Harper’s knowledge of Wright’s payment to Duffy.

“Yesterday the prime minister said that he did not learn about his chief of staff’s $90,000 payment to Mike Duffy until Wed. May 15,” Trudeau said. “Yet, media contacted his office on the afternoon of Tuesday the 14th to comment on the payment. His office and Mike Duffy then released identical statements on the source of that payment. How does the prime minister reconcile his assertion that he did not know about the scandal until Wednesday if his office responded the afternoon before?”

Harper said he was only informed “of this particular matter on the morning of May 15, that is why I did not know that on the afternoon of May 14.”

Until May 15, Harper said, “it was my understanding, this caucus’s understanding, this government’s understanding that Mr. Duffy had repaid his expenses using his own resources.”

Harper maintained that stance on Thursday when asked about the scandal by reporters during a joint press conference with visiting Chilean President Sebastian Pinera. Harper also deflected questions about what, if any, instructions he gave to staff to deal with the unfolding crisis.

Liberals lead in support

The poll also looked into support for the federal political parties and found that, if an election were held tomorrow:

36 per cent of decided voters would vote for the Liberals, up percentage one point from last month.

30 per cent would vote for the Conservatives, down two points.

27 per cent would vote NDP, up two points.

4 per cent would vote for the Bloc, down one point, while 4 per cent would vote for the Green Party, up one point.

Nearly four in 10 respondents said they either “strongly” or “somewhat” approve of the Conservative government’s performance, down four points from last month, while six in 10 either “strongly” or “somewhat” disapprove of the government’s performance.

The poll found that 31 per cent of respondents believe that the Harper government “has done a good job and deserves re-election,” down from 42 per cent in December 2010. About 69 per cent said it is “time for another federal party to take over,” up from 58 per cent.

On leadership attributes: