As the Senate scandal continues to dominate the agenda on parliament hill and just days before the Conservative policy convention in Calgary, Conservative support has stalled and Stephen Harper's personal brand has taken a hit, according to the latest Nanos Party Power Index.

The number:

53

The Conservative score on the latest Nanos Party Power Index

Source: Nanos Party Power Index,  Four week rolling average of 1,000 Canadians random telephone (land & cell lines) survey ending Oct. 25, accurate +/-3.1 percentage points 19 times out of 20.

Nanos Research releases a new Party Power Index score each week. It's a combination of measurements of federal party brands based on questions about the parties and the leaders.

The score is on a scale between zero to 100 for each party.

The Liberals remain ahead on the Nanos Party Power Index, with a score of 59. The Conservatives are second with a score of 53 and the NDP third at 46. The Green Party and Bloc Quebecois are trailing with scores of 32 and 26 respectively.

These results are based on random telephone (cell and land-line) interviews with 1,000 Canadians using a four-week rolling average ending Oct. 25, and is accurate to within 3.1 percentage points, 19 times out of 20.

Party Power Index Score

Source: Nanos Party Power Index, Four week rolling average of 1,000 Canadians random telephone (land & cell lines) survey ending Oct. 25, accurate +/-3.1 percentage points 19 times out of 20. (CBC)

In the lead up to the throne speech and before Parliament was sitting, Prime Minister Stephen Harper's personal numbers were growing, Nik Nanos told Evan Solomon on Power & Politics Wednesday. Harper was able to talk about consumer issues and trade, and it was working for him in the polls.

But the latest revelations from the Senate, in particular Senator Mike Duffy and the not one but two cheques he was given by Nigel Wright and the Conservative Party, have caused Harper's personal brand numbers to stall.

"The previously positive trend line for him [Harper] personally has gone flat," Nanos said.

Voter support numbers

But despite the controversy in the Senate, it's not all terrible news for the Conservatives.

When respondents were asked which federal party they would consider voting for the Conservative numbers have not changed.

Liberals are in the lead with 50 per cent. The NDP are second at 42 per cent, the Conservatives are a close third at 41 per cent. The Green Party is fourth at 24 per cent and the Bloc is sitting at 30 per cent in Quebec.

"So far the Tory core is still with Stephen Harper. They have not moved any place else," Nanos said, adding that this is the number to watch in the coming weeks as the controversy in the Senate continues. 

"Right now, the damage is primarily on Harper's personal brand, not on Conservative support," Nanos said.

NDP Leader Tom Mulcair has been relentless in question period over the past two weeks, and Nanos said Mulcair's individual numbers are good and are starting to move up.

"For Thomas Mulcair, he has to repeat his fairly effective performance in the House of Commons over and over and over again in order to have that cut through and zero-in for Canadians to see."

In the days ahead, as long as the Senate scandal is about Stephen Harper, it's going to be a problem for him and right now the controversy is about his credibility, Nanos said.

Strictly looking at the numbers "this issue is a significant challenge to Stephen Harper's ability to win a majority government."

Nik Nanos digs beneath the numbers with CBC News Network's Power & Politics to get to the political, economic and social forces that shape our lives. Recognized as one of Canada's top research experts, Nanos provides numbers-driven counsel to senior executives and major organizations. He leads the analyst team at Nanos, is a Fellow of the Marketing Research and Intelligence Association and a Research Associate Professor with SUNY (Buffalo).