Conservative Leader Stephen Harper and his wife Laureen depart the campaign plane in Toronto, Monday September 7, 2015. THE CANADIAN PRESS/Adrian Wyld

OTTAWA - The Conservatives stumbled as the federal election reached an unofficial milestone on Monday, dropping two candidates from their slate in the important Greater Toronto Area battleground after embarrassing videos surfaced in the mainstream media and online.

Jerry Bance, who was running in Scarborough Rouge Park, was the first to go after reportedly being caught on camera urinating into a coffee cup while he was an appliance repairman.

The day got worse as Tim Dutaud, the candidate in Toronto-Danforth, was declared persona non grata by the federal party a short time later.

A Conservative official confirmed a man seen making prank calls in several YouTube videos — including one where he pretends to have a mental disability — is Dutaud.

The revelation came just before Prime Minister Stephen Harper said re-elected Conservatives would improve a federal disability grant program, one championed by Jim Flaherty, the late finance minister.

And in Quebec, the Bloc Quebecois was critical of Conservative candidate Mohammad Zamir, who was spoke in garbled French during two interviews with La Presse Canadienne.

His unilingual English website, which has since been taken down, said he spoke "elementary" French.

During a campaign stop in Mississauga, Ont., Harper tersely attempted to put the best spin on the losses when asked what the incidents said about the quality of candidates he was attracting.

"What this says is that we keep the highest standard for candidates and these two individuals are no longer candidates," said Harper, who later in the five-question availability indicated that the Conservatives would find replacements for both ridings.

Bance, who runs an appliance repair company, was bounced from the Conservative slate after the CBC reported its hidden cameras on the show "Marketplace" caught him urinating into a cup while he was on a service call in 2012. Video from the program shows Bance pouring the urine down the sink, then rinsing out the cup, all while the homeowner was in the next room.

A statement from Bance released by the Conservative campaign Sunday night said he "deeply regrets" his actions on the day he was caught on the hidden cameras.

NDP Leader Tom Mulcair cracked a joke in response, saying Bance must be in favour of Harper's "trickle down" economics.

The developments all came as the election campaign shifts into a higher gear.

For political junkies and pundits, Labour Day is supposed to be the demarcation line between the sleepy summer campaign that began on Aug. 2 and the serious push to get the attention of voters ahead of Oct. 19.

It is also the beginning, in earnest, of the labour movement's effort to unseat the Conservatives by bidding members to vote strategically in key battleground ridings.

Union leadership at Unifor, in Ontario, urged its rank and file to help elect incumbent NDP candidates and vote strategically in other ridings where the polls are close. The Quebec Federation of Labour, meanwhile, said it plans to help any candidate that can defeat Conservatives in that province.

Mulcair burnished his party's union support by taking part in Toronto's Labour Day parade, the largest in the country.

"Mr. Harper has led a series of unprecedented attacks on labour in this country," Mulcair said. "We have a different approach. We know by working together, we can achieve great things."

Justin Trudeau, also campaigning in Mississauga on Monday, was asked if labour's stampede to get rid of the Conservatives would trample over Liberals and go right to the NDP.

He dismissed the notion, saying he's met with labour organizations across the country and looks forward to them voting Liberal.

News from © The Canadian Press, 2015