That could put the Conservative brand at risk, along with the defence invoked by Conservatives as they kick off the party's biannual policy convention in Calgary.
Many Conservatives arriving at the convention yesterday pointed to Harper's economic management when asked how they felt about the Senate scandal.
But a new Nanos Research poll suggests that's not how many Canadians feel.
Just over half — 51 per cent — of those surveyed said Harper's management of the Senate controversy was more important to judging his performance than his track record on job creation. That compares with 37 per cent who said job creation was more important to judging his performance than his handling of the Senate scandal. Twelve per cent said they weren't sure which was more important.
Those numbers have flipped since a June 2013 survey by Nanos, which found that 39 per cent of those polled said the Senate scandal management was a more important factor in judging Harper's performance, and 45 per cent named his promotion of an environment in which jobs were created.
The Nanos Research survey of 1,000 Canadians was conducted Oct. 26-30, 2013. Participants were randomly recruited by both landline and cellphone, and administered a survey online. The results were statistically checked and weighted using the latest census data. The margin of error for a random survey of 1,000 Canadians is plus or minus 3.1 percentage points, 19 times out of 20.
Nik Nanos, president of Nanos Research, said the scandal could be a defining point in Harper's mandate if it goes on to become a ballot box issue in the 2015 election.
"It has to be a significant blow considering all the effort that he has put into building his personal brand about being a good economic manager," Nanos said in an interview with CBC News.
The issue could live on if there are more revelations, Nanos said, or fade if there's nothing new to feed it.
"What Harper has to worry about is that this issue comes as death by a thousand paper cuts, that there are new twists and turns and revelations over the next year that keep him off-balance and don't allow him to kind of rebuild his personal brand," he said.
The survey also found 76 per cent of respondents are dissatisfied or somewhat dissatisfied with Harper's explanation that he didn't know about his former chief of staff, Nigel Wright, giving Senator Mike Duffy a cheque for $90,000 to repay questionable expenses.
Only 21 per cent of respondents were satisfied or somewhat satisfied with his explanation.
Last June, 27 per cent of respondents were satisfied or somewhat satisfied, and 72 per cent were dissatisfied or somewhat dissatisfied.
On the question of how closely they follow the controversy over Patrick Brazeau, Duffy and Pamela Wallin's Senate expenses, 48 per cent said they followed it closely. Another 35 per cent said they followed it somewhat closely, while 16 per cent said they followed it not closely or "somewhat not closely."
When it came to choosing an area that most concerned them, 55 per cent of respondents chose the conflicting stories about Harper's role in and knowledge of the cheque from Wright to Duffy. Thirty per cent said the questionable expenses claimed by the three Conservative-appointed senators were of most concern to them.
Seven per cent said the fact the prime minister's chief of staff wrote a cheque to a senator was of most concern to them, with six per cent said none of those scenarios concerned them.