The Nanos Research tracking poll of results for three days of surveys put support for the Conservatives at 36.4 percent, down a touch from 36.6 percent in Thursday's poll.
The NDP had 31.2 percent of decided voters, up from 30.4 percent in Thursday's survey, and continued to trend up in Ontario and British Columbia.
The NDP has come from well behind to a solid second place in the polls but it is possible the party's rise could split the center-left vote with the Liberals and hand the Conservatives a majority of seats in the House of Commons.
Under Canada's electoral system, a party normally has needed to win about 40 percent of the national vote to win a majority of the 308 seats in the House of Commons.
The Nanos poll showed Liberal support little changed, at 22.0 percent, from 21.9 percent in Thursday's poll.
Nanos said the separatist Bloc Quebecois, which runs candidates only in Quebec, was at 5.7 percent, down slightly from 6.0 percent in Thursday's poll. NDP support in Quebec was down slightly but remained at a lofty 41.4 percent, with the Bloc Quebecois at 23.6 percent.
The national daily Nanos tracking figures are based on a three-day rolling telephone sample of 1,021 decided voters and are considered accurate within 3.1 percentage points 19 times out of 20.