QUEBEC -- Liberal Leader Justin Trudeau is promising a bump in federal aid to low-income seniors if re-elected, appealing to an age cohort most likely to cast a ballot with a pledge that could also help him in key Quebec races.

Trudeau's pledge would see the guaranteed income supplement rise by $500 a year for individuals, and $750 for senior couples, reaching some 2.2 million seniors who receive the old-age benefit.

The Liberals didn't detail how much the measure would cost.

The first time the Liberals gave a bump in benefits to the country's poorest seniors, the measure was credited for lifting some 57,000 retirees out of poverty, although many of them moved barely above the poverty line.

On Thursday, Trudeau argued that an extra $42 per month for individuals would make a material difference in their lives.

"Unfortunately, we know that for many, many seniors, every dollar counts," Trudeau said.

"That's been particularly clear during this pandemic where our seniors have been unbelievably vulnerable both to COVID itself, to the isolation they felt, but also with extra costs they've had to absorb."

The number of Canadian seniors has reached record levels, and their ranks are only expected to grow as more people retire and live longer in retirement -- a double-whammy for federal costs.

As a result, spending on old age security and the low-income supplement is expected to rise from $62.5 billion this year to $81 billion in 2026, based on the projections in the spring budget.

That budget also made good on a 2019 campaign promise to raise old age security payments by 10 per cent for seniors over the age of 75. It estimated that would provide an extra $766 in benefits to 3.3 million retirees, but that doesn't kick in until next year.

In the meantime, the Liberals sent one-time payments of $500 to the country's oldest seniors to hold them over until next year, with the payments landing in bank accounts beginning the day after Trudeau started the election campaign.

NDP Leader Jagmeet Singh criticized Trudeau's announcement, noting that benefits for low-income seniors had been cut if they received emergency benefits, which pushed up income used to calculate the value of seniors' benefits.

"If Justin Trudeau wants to make life better for seniors, he should start today by reversing his cuts to income assistance for seniors," Singh said in a statement.

Seniors are always a critical constituency in an election because they turn out to vote in higher numbers. In the 2019 election, 79 per cent of those between 65 and 74 voted, well above the overall turnout rate of 67 per cent as reported by Elections Canada.

Their votes could be doubly important for the Liberals in Quebec with candidates in tight races, including with the Bloc Quebecois. That party supports boosting benefits for seniors, but Trudeau demurred when asked why he could not have proposed the measure in a minority Parliament.

Jean-Yves Duclos is one of the Liberal ministers in a tight race with the Bloc, having barely won his riding of Quebec in 2015 and again in 2019.

The former academic had studied the effects of federal policy on seniors' poverty rates, and his work was part of the decision by the Liberals to set the age of eligibility for old age security at 65, rather than 67 as the previous Conservative government proposed.

But between Thursday's announcement for more money for seniors and billions for the province's publicly funded child-care system, Duclos was asked if the Liberals weren't just copying-and-pasting from the Bloc's playbook to wedge them in Quebec.

"The Bloc Quebecois speak. We act," Duclos told reporters after the event.

"(Bloc Leader Yves-Francois) Blanchet has never been invited to the federal cabinet to defend the interests of Quebecers, so he can say whatever he wants. We're there to help people in Quebec."

Trudeau made a stop in Trois-Rivieres later Thursday, speaking to a small group of supporters on an outdoor patio alongside his industry minister, Francois-Philippe Champagne, and the local candidate, Martin Francoeur, who found himself in the Conservatives' crosshairs.

The Tories noted that last year Francouer had written a critical editorial about the WE Charity affair and questioning Trudeau's ethics.

Speaking to reporters, Francouer suggested he had no concerns about that now following an ethics commissioner's review.

"If I had any doubt about the integrity about either the leader of the party or any member, I would not have been candidate for the Liberal party," Francouer said.

This report by The Canadian Press was first published Aug. 26, 2021.