OTTAWA - Prime Minister Stephen Harper's Conservatives are losing ground to Liberals and New Democrats in provinces that will hold the key to electoral victory, a new poll suggests.

The Canadian Press-Harris-Decima survey indicates that the Liberals maintained a slim, three-point lead over the Tories nationally.

But the Tories yielded political turf in Quebec, Ontario and British Columbia, the provinces most likely to determine the outcome of the next election.

"Nationally, the numbers appear to be quite stable," said Harris-Decima senior vice-president Jeff Walker.

But he added: "Gaining votes matters most where parties can increase their number of seats and the Liberals are gaining where they need seats whereas the Conservatives are not."

Nationally, the Liberals were at 32 per cent, the Tories at 29 per cent, the NDP at 16 per cent, the Greens at 11 per cent and the Bloc Quebecois at nine per cent.

But in Ontario, which accounts for one-third of the seats in the House of Commons, the Conservatives were nine-points behind the Liberals, with 31 per cent and 40 per cent respectively. The NDP had 15 per cent support and the Greens 14 per cent.

In Quebec, the Tories have fallen to a distant third, with 12 per cent support compared to 40 per cent for the Bloc, 31 per cent for the Liberals, nine per cent for the NDP and five per cent for the Greens.

And in B.C., the Tories have slipped into a second-place tie with the Liberals (26 per cent each), while the NDP has pulled into a slim lead with 29 per cent support. The Greens had 16 per cent.

In Atlantic Canada, the Liberals continued to maintain a strong advantage, with 41 per cent, compared to 27 per cent for the Tories, 25 per cent for the NDP and six per cent for the Greens.

The only bright spot for the Conservatives was in the Prairies, where they already hold all but seven seats and, thus, have little to gain.

In Alberta, the poll suggests the Tories continued to dominate with 55 per cent support, compared to 19 per cent for the Liberals, 14 per cent for the Greens and 10 per cent for the NDP.

In Manitoba-Saskatchewan, the poll pegged Conservative support at 46 per cent, to 23 per cent for the Liberals, 16 per cent for the NDP and 11 per cent for the Greens.

Walker said the Tories' slide in key battleground provinces can be traced in large part to a loss of support among women voters, particularly those in large urban centres.

"This is the audience who's actually moving. Men aren't moving very much. They pretty much know who they're voting for," Walker said.

The poll suggests 34 per cent of female respondents supported the Liberals, versus 28 per cent for the Tories. Among urban women, Liberals enjoyed a nine-point advantage, 37 per cent to 26 per cent for the Tories.

The survey of just over 2,000 respondents was conducted April 8-9.

The national portion is considered accurate within 2.2 percentage points, 19 times in 20.

Provincial findings have higher margins of error: 3.8 percentage points for the Ontario results, 4.4 points for Quebec, 6.1 points for B.C., 6.8 points for the Atlantic, 6.9 points for Alberta and 6.9 points for Manitoba-Saskatchewan.

More information on the survey can be found at www.harrisdecima.com.