Two new polls suggest Prime Minister Justin Trudeau, leader of the Liberal Party, has lost ground to Conservative rival Andrew Scheer ahead of Canada's October 21 election.

The polls are the first to be released since images of Trudeau in blackface emerged, a scandal that has threatened to derail the prime minister's reelection campaign.

Election neck-and-neck

Scheer holds a 4.8 percentage-point lead over Trudeau, according to a Nanos Research poll published on Saturday for CTV and the Globe and Mail newspaper, up from a 3.2 percentage-point lead in the previous survey published on Friday.

Conservatives would win 36.8 percent of the vote and the Liberals 32 percent, the poll suggested.

The Nanos poll was conducted over three nights until September 20. The first image of Trudeau in blackface at a 2001 "Arabian Nights" party when he was a 29-year-old teacher were published on the evening of September 18.

The Liberals remained ahead in a Mainstreet poll published by iPolitics on Saturday, but had lost 0.4 percentage points from the previous survey compared with a 0.2 percentage-point slide for the Conservatives.

The Mainstreet poll, conducted between September 17 and 19, had the Liberals at 36.8 percent compared with 34.2 percent for the Conservatives.

The Canadian Broadcast Corporation's poll tracker, which aggregates public polls, had the Conservatives at 34.8 percent and Liberals at 33.8 percent on Saturday.

Will Liberals turn out?

Polling suggests that few Liberals are likely to cross over to the Conservatives as a result of the blackface scandal, but some may switch to smaller parties and others may not turn out to vote.

A survey by consumer research firm Potloc indicated soft Liberal voters were most likely to back either the left-leaning New Democrats or the Greens.

Pollster David Coletto of Abacus Data said the real risk might be Liberal supporters that stay home on election day.

"I don't see a big flight away from the Liberals or a collapse in their support," Coletto told Reuters. "But there is certainly the chance that this further demotivates those Liberals and makes them less likely to want to actually cast a ballot."

(With input from Reuters)