An NDP surge following the party's leadership convention has put them in a statistical tie with the federal Conservatives, a new poll suggests.

The Nanos Research monthly tracking poll puts the Conservatives at 34.7 per cent and the New Democrats at 32.4 per cent of committed voters, within the poll's margin of error of plus or minus 3.2 percentage points, 19 times out of 20.

The Liberals are at 23.3 per cent, according to the poll, the Greens at 4.2 per cent and the Bloc Québécois at 3.9 per cent of committed voters. Almost 19 per cent of voters said they were undecided.

The poll suggests the Conservatives' popularity slipped one percentage point — well within the margin of error — from a previous poll of 1,203 Canadians conducted in February, while the NDP are up 7.4 percentage points.

Prime Minister Stephen Harper's leadership numbers, however, appear to have dropped dramatically. While 31.7 per cent of those polled two months ago said he was most trustworthy party leader, that number fell to 20 per cent in April.

When respondents were asked who was the most competent leader, Harper dropped almost 14 percentage points from 38.1 per cent to 24.2 per cent. And Harper dropped 11 percentage points, from 32.6 per cent of respondents feeling he had the best vision for Canada's future, to 21.6 per cent.

"This is the lowest score that Stephen Harper has ever received in four years," said Nik Nanos, president of Nanos Research.

"He has been the Teflon prime minister. He has weathered a lot of storms and controversies, and nothing has ever stuck to him."

One data point on a trend line

Lately, Harper has been dealing with controversies over fraudulent election telephone calls, which opposition MPs say came from the Conservative Party, and the cost of 65 F-35 fighter jets, for which the auditor general found defence officials hid the cost.

It's important to note this poll is one piece of information on a longer trend line, Nanos said.

"There’s a very unusual confluence of a 24-hour NDP infomercial known as its convention and controversies for the Conservatives at the same time," Nanos said.

"Realistically, we should be waiting to see whether this is the new normal or whether this is a one-off, isolated event."

New NDP Leader Tom Mulcair, who won the party's leadership at the end of March, is close behind Harper on the trust indicator, coming in with 19.5 per cent support. The poll shows 17 per cent of Canadians see him as most competent and 17.3 per cent say he has the best vision for Canada.

Harper remains ahead of Mulcair on leadership scores, Nanos pointed out.

"But Stephen Harper’s competence score has dropped 14 points in a very short period of time."

Interim Liberal Leader Bob Rae took 13.6 per cent on the trust indicator, 12.2 per cent in competence and 10.7 under vision for Canada. Those numbers are down about six percentage points across the board.

One-fifth undecided

Canadians don't seem all that pleased with any of the leaders, however: asked who was most trustworthy, 15.8 per cent said "none of them" and 20.6 per cent were undecided. Those answers added together are more popular than any of the leaders.

Asked which leader is the most competent, 15.8 per cent said no one and 24.4 per cent said they were undecided.

As for who has the best vision for Canada, 15.2 per cent said none of them and 27.1 were undecided.

Asked what their most important national issue of concern was, 21.9 per cent of those polled said jobs or the economy, down 3.9 percentage points from the last poll in February.

Another 21.6 per cent said healthcare was of most concern, up 5.7 percentage points. Just over 10 per cent mentioned education, up 4.7 percentage points, 9.3 per cent said the environment, up 2.9 percentage points and 5.1 per cent said high taxes, up 2.1 per cent. Respondents were not prompted with a list of possible answers.

Nanos conducted a random phone survey of 1,200 Canadians 18 and older from April 13-18, 2012. The questions on leadership qualities and issues of importance to Canadians have a margin of error of plus or minus 2.8 percentage points, 19 times out of 20.

The results for the question on which party Canadians would vote for have a higher margin of error because they are based on a smaller sample of 975 committed voters.