The federal Conservatives and the New Democrats are neck-and-neck in terms of overall support from Canadians, a new poll finds, despite Prime Minister Stephen Harper's personal brand getting a boost from undecided voters.

As MPs return to Ottawa for the fall sitting of Parliament, the Nanos Research survey also shows that more Canadians are listing jobs and the economy — a Conservative plank — as their top concern.

"Harper had to manage a number of controversial issues such as the F-35 file, the omnibus budget bill, and the robocalls affair — all of those things incrementally had a a bit of an erosion effect on Conservative support," pollster Nik Nanos of Nanos Research told CBC News.

The phone survey shows that 32 per cent of committed voters would consider voting for the Tories, compared to 30 per cent who would consider casting a ballot for the New Democrats, 25 per cent for the Liberals, and five per cent for the Greens.

According to Nanos, the trend for the past year shows "the Conservatives have been slowly eroding support" while the NDP, under Tom Mulcair, has been able to hold on to many of the gains they made under [former NDP leader] Jack Layton in the last federal election."

While the Liberal leadership race doesn't formally get underway until November, Nanos said "the Liberals are going to be the one party to watch."

The question is whether their leadership process will generate any kind of excitement or interest with voters and that's "a big question mark right now," said Nanos

Jobs and the economy

More Canadians say they are preoccupied with jobs and the economy than with the environment, a finding Nanos said tends to help the Conservatives.

The survey showed that 30 per cent of Canadians listed jobs and the economy as their top national issue, compared to nine per cent who listed the environment.

According to Nanos, the key take-away here for the NDP is "the environment is important for many Canadians. However, more Canadians would like to hear from all parties on jobs and the economy."

Results showed three per cent of Canadians listed the debt and deficit as their top national issue, while 12 per cent were unsure.

Leadership

Finally, it appears that Harper and the Conservatives benefitted the most from Parliament adjourning for the summer.

Nanos calculates a "leadership index" based on how the federal party leaders are polling on matters of trust, competence and vision for Canada.

Harper's leadership score is up 20 points over the summer, currently sitting at 93 compared to leadership index scores of 48 for NDP Leader Tom Mulcair and 38 for interim Liberal Leader Bob Rae that did not change significantly over the summer.

Nanos explained that Harper's personal brand received a boost, not to the detriment of the other federal parties, but in large part from voters who said they were previously "undecided" or chose "none" of the leaders.

"The summer allowed Harper and the Conservatives to do a little brand repair," said Nanos.

"For one, when the House of Commons doesn't sit, governments usually do better. And two, it's very difficult for opposition parties to sustain negative attacks on the government when Parliament isn't sitting."

According to Nanos, these numbers will move depending on whether the government makes any more mistakes, and depending on how effective the opposition parties are in the fall sitting.

"It's a test on both sides," said Nanos.

Nanos Research conducted a random telephone survey of 1,000 Canadians 18 years of age and older between Sept. 4-9, 2012. The poll is accurate within a margin of error of 3.1 percentage points, plus or minus, 19 times out of 20.

A separate telephone poll conducted by Harris-Decima for The Canadian Press between Aug. 30 and Sept. 10 with a sample size of 2,007 suggests a bigger gap between Conservative and NDP support, with 34 per cent of respondents indicating support for the Conservatives, the NDP at 27, the Liberals at 24 and the Greens at seven.