WINDSOR, ONT -- Liberal Leader Justin Trudeau made an appeal to progressive voters in southern Ontario on Friday morning, but was forced to face questions about a past sexual assault charge against one of his candidates that was later dropped.

Speaking in Windsor, Ont, Trudeau said Spadina-Fort York candidate Kevin Vuong has been asked to "pause" his campaign after the party learned about the allegations.

"We are a party that always takes seriously any allegations or reports of sexual harassment or intimidation or assault," Trudeau said. "That has been clear from the very beginning."

He said his party had not been aware of the charge until Thursday, when the Toronto Star published a report on the matter.

"We are looking into it very carefully and we have asked the candidate to pause his campaign," he said.

The Defence Department confirmed late Friday that the military is reviewing whether Vuong, who is listed as a naval reservist, reported his arrest to his chain of command, as he would be expected to do. "As things stand, we are looking into the matter further," Daniel Le Bouthillier wrote in an statement sent by email.

Earlier Friday, Vuong said in a statement that the allegations are false.

"I vigorously fought these allegations when they were initially brought forward. The allegations were withdrawn. Had they not been withdrawn, I would have continued to defend myself against these false allegations," he said.

"This resurfacing three days before the election is deeply troubling to me and my family. I will be taking some time with my family."

Vuong could not immediately be reached Friday night to respond to the news of the Defence Department's review.

Court documents confirm Vuong was charged with sexual assault in 2019 and that the charge was withdrawn later that year.

Brian Gray, a spokesman for Ontario's Ministry of the Attorney General, said in a statement that, in general, the Crown "has a duty to assess the strength of a case throughout a prosecution, and is duty bound to withdraw charges if there is no reasonable prospect of conviction, or if it is not in the public interest to proceed."

The Conservatives and the NDP both sent out statements criticizing Trudeau and calling for Vuong to be booted from the Liberal party.

"By defending this candidate, Justin Trudeau is still putting the ambitions of himself and other men over the lives and well-being of women," NDP Leader Jagmeet Singh said in a statement.

The Conservatives, for their part, accused Trudeau of hiding the charge form Canadians and called on the Liberal leader to promise that Vuong would not sit in the Liberal caucus if elected.

Trudeau did not specifically answer a question about whether Vuong would be fired, saying the party still had "questions about exactly what happened."

"We are looking into that very rapidly," he said.

Spadina Fort-York was previously represented by Liberal Adam Vaughan, who is not running again in 2021. The report comes after many Canadians have already voted in advance polls and mail-in ballots.

Trudeau chose to highlight the theme of sexual assault at an afternoon whistle stop in London, where he expressed support for the thousands of Western University students who walked out of classes on Friday to protest what organizers call a "culture of misogyny" on campus.

"It's not OK for women to feel unsafe in classrooms, in workplaces," Trudeau told the crowd on a restaurant patio, before pointing out that he was one of the first male volunteers at a student society sexual assault centre during his own university days at McGill some 30 years ago.

Trudeau was greeted in both Windsor and London by small groups of protesters who hurled insults his way. In Windsor, about two dozen people chanted "traitor!" at Trudeau, whose supporters tried to respond by chanting the leader's name. In London, a man with a megaphone shouted "masks are ineffective!" and said it was his duty to oppose "tyrannical laws."

In both cases, the Liberal leader ignored the protesters and went on greeting supporters.

The questions around the candidate came as the leaders are making their pitch to voters in the final days of the campaign.

At the event in Windsor, Trudeau said he "took it personally" in 2019 when experts labelled the NDP and Greens' climate plans as more ambitious than his own.

"It really bugged me that in 2019 the experts came out and looked at the various parties' climate plans and said, 'the Liberal party has a great ambitious, concrete deliverable plan to fight climate change, sure, but the NDP and the Green party have more ambition in their plan,"' he told reporters.

He said the experience motivated him to create his new plan, which he says is not just more concrete and realistic than the other two parties' plans, but also more ambitious.

Trudeau spoke of his climate plan as he made a pointed plea to voters considering the New Democrats or the Green Party in the final days of the campaign.

He said the Liberal party is the only one that can stop the Conservatives from governing, and also the one with the best plan, meaning voters are no longer facing the "impossible choice" of whether to vote strategically.

"I will ask progressives across the country who are maybe thinking about voting for the NDP or Green Party to think about the top issues they are concerned with for the future," Trudeau said.

The Liberals are promising a 40 to 45 per cent reduction in greenhouse gas emissions over 2005 levels by 2030 -- a target submitted to the United Nations earlier this year.

The Conservatives are promising a 30 per cent reduction, while the NDP is promising 50 per cent and the Greens are promising 60 per cent.

Later Friday, Trudeau blitzed his way through several southern Ontario cities as he racked up another high-profile endorsement from south of the border.

One day after former U.S. president Barack Obama expressed his support for Trudeau, former secretary of state Hillary Clinton did the same, praising his leadership on accessible child care, reproductive rights and action on climate change.

"I'm wishing him and our progressive Canadian neighbors the best in Monday's election," she wrote of Trudeau on Twitter.

This report by The Canadian Press was first published Sept. 17, 2021.