The Conservatives are leading the second-place Liberals by 16 points, suggests the most recent four-day Canadian Press Harris-Decima poll, released Sunday.

That's up two percentage points over the past week.

The national poll suggests the Conservatives are supported by 39 per cent of voters, compared with the Liberals at 23 per cent.

   Percentage of respondents supporting each party
 Party  Sept. 17-20  Sept. 10-13
 Conservative  39  40
 Liberal  23  26
 NDP  17  15
 Green  11  9
 Bloc  8  8
 Source: Canadian Press Harris-Decima polls

The number of seats each party will win depends on the distribution of the votes among the 308 ridings.

The Tories have dropped one percentage point over a week, and the Liberals are down three points.

The NDP is up two points at 17 per cent, and the Greens are also up two points at 11 per cent.

The Bloc Québécois (BQ), which is running candidates in Quebec alone, is unchanged at eight per cent.

The figures were based on the question: "If a federal election were held tomorrow, who do you think you would be voting for in your area," and then lists the parties.

The average sample was 1,344 with a margin of error of plus or minus 2.7 per cent.

In terms of leaders, the NDP's Jack Layton ranked first and the Liberal's Stéphane Dion a distant fifth.

The poll calculates the leaders' rankings by subtracting the percentage of people who said they had an unfavourable impression of the party leader from the percentage saying they had a favourable impression.

Layton's ranking is 16, the BQ's Gilles Duceppe 12, the Green's Elizabeth May 10, the Conservatives' Stephen Harper four, and Dion minus 24.