The Conservatives are still enjoying a comfortable lead over the Liberals, the latest poll numbers suggest, but the Liberals may be catching up.

Tuesday morning's edition of the three-day rolling Nanos Research tracking poll, conducted for CTV and The Globe and Mail, shows the Liberals are up 2 percentage points to 30.2 per cent. That's now less than 10 points behind the Conservatives, who have 39.8 per cent support. The NDP is holding steady at 16.5 per cent.

The Conservatives previously held a 14-point lead in the poll. But because Tuesday's poll includes polling from Saturday, Sunday and Monday, the bump in Liberal support could very well reflect the impact of the recently-released Liberal platform.

The advantage enjoyed by Prime Minister Stephen Harper's Conservatives is primarily fuelled by ongoing support in the Prairies. With 54.1 per cent support in that region, they are well ahead of the Liberals, at just 28.9 per cent.

But outside the West, the Conservatives and Liberals are now almost statistically tied when the margin of error is taken into account -- particularly in battleground Ontario, where the Liberals are winning back ground.

The Liberals now have 41.1 per cent support in Canada's most populous province, compared to 39.6 per cent support for the Tories. The NDP is at 14.7 per cent in Ontario.

In Atlantic Canada, too, the Tories and Grits are running neck and neck, with 39.3 and 35.8 per cent support respectively.

In Quebec, the Bloc Quebecois continues to be the top vote choice. They enjoy 35.8-per-cent support, compared to the 22 per-cent support given the Conservatives. The Liberals and the NDP are effectively tied for third in Quebec, at 17.6 and 16.9 per cent support respectively.

Nanos' three-day tracking poll surveys 400 people a day, then tallies the results of the previous three days for a combined survey of 1,200 Canadians. Each day, samples from four days ago are dropped from the results, and the latest day's are added, to get the three-day rolling result.

Tuesday's sample was conducted April 2 to April 4.

This poll also asked potential voters about what was the most important factor influencing their vote.

About one of every two (48.0 per cent) said party policies was the most important factor. Almost 23 per cent said the party leader was the biggest factor in their decision, while 17.6 per cent said they gave the most consideration to the local candidate when they entered the voting booth.

Nanos Research says the sample is accurate to within 2.8 percentage points, 19 times out of 20.

Regional results have higher margins of error because of the smaller sample size – Ontario samples have a 5.6 percentage-point margin of error and Quebec samples have a 6.6-percentage point margin.