WATCH: Speaking in Trois-Rivières, Que., on Thursday, Liberal Leader Justin Trudeau wouldn't say whether his campaign team asked for an endorsement from former U.S. President Barack Obama, joking that "nobody tells Obama what to do."

Justin Trudeau would not say Thursday whether his team asked former U.S. president Barack Obama to endorse his bid to remain prime minister, which came as the Liberals fight hard to convince progressive voters to stick with them.

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“Barack Obama makes up his own mind,” Trudeau said during a campaign stop in Trois-Rivieres, Que., when asked directly if he had sought the endorsement, which highlighted his choice to take on climate change as a major issue. The day before, Obama had voiced his support for Trudeau on Twitter.

READ MORE: Barack Obama endorses Justin Trudeau in Canadian federal election

The clock is ticking down to the Oct. 21 vote, with public opinion polls suggesting neither the Liberals nor the Conservatives is heading for a majority government. Trudeau has been working hard to convince progressive voters to cast their ballots for the Liberals, as the polls also suggest many are leaning toward the NDP and the Greens, and, in this province, a resurging Bloc Québécois.

The Liberals see the friendly nod from the past U.S. president as underscoring their argument that, despite any disappointments voters might have, or desire to move more quickly on progressive issues, they should vote for Trudeau if they do not want Conservative Leader Andrew Scheer in charge.

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The endorsement also sparked some controversy at a time when concerns about foreign interference in democratic elections are prominent for many governments and voters, which is why Trudeau is facing questions about how it came about.

During an interview with Celine Galipeau, the news anchor for Radio-Canada in Montreal, on Thursday afternoon, Trudeau urged progressive voters to give him more time.

“There is still a lot to do and people are impatient, and I understand, but the choice is whether we continue to invest, or go back to cuts,” said Trudeau.

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The Liberal leader was then asked whether this election is a referendum on his leadership, after a series of controversies like his trip to India — with its costumes and the attempted assassin invited to events — and how he handled the SNC-Lavalin affair.

“I have never pretended to be perfect,” he said, “but I think people know that the values and the approach I have, to invest and build a stronger society, and defend the rights of everyone, they can always count on that.”

Earlier Thursday, Trudeau was asked whether he had apologized to Obama, the first African-American to be elected U.S. president, for having worn brown- and blackface in the past.

Trudeau responded by saying the last time he spoke to Obama, who also endorsed Emmanuel Macron’s successful bid for the French presidency, was in the spring when the former president delivered a speech in Ottawa.

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Last month, Time magazine published a yearbook photo of Trudeau in dark makeup at a 2001 “Arabian Nights” party organized by West Point Grey Academy, the Vancouver private school where he was a teacher. Two more instances of Trudeau wearing blackface quickly emerged.

Trudeau has apologized for wearing the makeup, which he says he now believes is racist.

Trudeau spent Thursday campaigning in Quebec, where the Liberals won 40 of 78 seats in 2015. That success played a major role in delivering them a majority government.

The sudden rise of the Bloc Quebecois, led by Yves-Francois Blanchet, is posing a threat to the Liberals’ ability to form another one, which is one reason Trudeau has been going extra hard against the Bloc.

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Liberal candidate Francois-Philippe Champagne, a cabinet minister seeking re-election in Saint-Maurice-Champlain, decried the argument from the Bloc Quebecois that they can be a stronger voice for the province.

“Does anyone believe that?” Champagne said in Trois-Rivieres on Thursday.

“Honestly, I would say I think Quebecers want to decide for themselves and deciding for yourself is being in government,” he said.

“The nature of the opposition is asking questions in the House. The nature of government is to govern, is to reflect what Canadians want, so I’m very confident that Quebecers want to decide for themselves,” he said.

Marianne Rousseau, 18, gets to choose for herself for the first time Oct. 21, as this is the first election since she became old enough to vote.

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Trudeau sat down with her for a few moments as he was making his way through a crowded restaurant in Terrebone, Que., people asking for photos as they ate bacon and eggs.

Rousseau said she told Trudeau that the environment is her main concern.

“If we have a government that is ready to make changes, it will be better for the next generation,” said Rousseau, adding that she liked what he had to say.

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“I think I am going to vote for him,” she said.

While some of the election discussion has shifted toward the scenarios in which either the Liberals or Conservatives would be able to form a minority government, Trudeau refused to weigh in, saying he remains focused on winning a strong Liberal government.

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