But the Nanos survey also suggests Canadians are already turning their attention back to the economy.
"I think what we're starting to see is the new trend, the new normal ... with the Trudeau-led Liberals in the lead," said Nik Nanos on CBC News Network's Power & Politics.
In a national telephone survey, the Liberals received 36 per cent support, an increase of two percentage points from June. Conservatives held on to 30 per cent of the decided vote, compared to 29.4. per cent in June, and the NDP was steady at 25 per cent support.
"The good news for the New Democrats is that they're still in striking distance [of the Conservatives]," said Nanos.
Nanos Research polled 897 committed voters who were recruited by phone and administered an online survey between Aug. 18 and 22. The margin of error is 3.3 percentage points, 19 times out of 20.
The Senate scandal hurt support for the Conservatives, benefiting the Liberals, Nanos told Power & Politics host Evan Solomon.
But Trudeau hasn't seen a rise in popularity after focusing on marijuana, Nanos added. The Liberal leader was in the news recently for admitting he smoked marijuana a few years ago, after he was elected as an MP. The Liberal party is pushing for the legalization of marijuana.
Trudeau's pot admission and policy is "statistical puffery" because it drives interest but not votes, Nanos said.
Canadians focused on economy, Senate interest dying down
But there has also been a spike in Canadians' focus on the economy, according to Nanos.
Nanos Research's survey shows that 35 per cent of Canadians said the economy is their top priority, which is an increase of 11 percentage points from June.
Meanwhile, only 17 per cent said corruption in the Senate was top priority, compared to 19 per cent in June.
The survey of 1,000 voters has a margin of error of 3.1 percentage points, 19 times out of 20.
In order to gain support with Canadians, the Conservatives need to reinforce their brand as the party in control of the economy, while getting a handle on the Senate scandal, Nanos said.
Opposition parties also need to strategize their attacks and policy around the economy and jobs, according to Nanos.
"For the Liberals, don't be smug, Nanos said. "You have to have a plan, a vision, something related to the economy."
The economy will "make or break the political futures of all the federal party leaders," Nanos said.
Recognized as one of Canada's top research experts, Nik 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, a research associate professor with SUNY (Buffalo) and a 2013 public policy scholar with the Woodrow Wilson International Center for Scholars in Washington DC.
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