OTTAWA -- The anticipated flood of Canadians choosing to vote by mail on Sept. 20 has been more of a trickle so far.

As of Wednesday evening, Elections Canada had issued 344,656 special ballot kits.

That's more than six times the roughly 50,000 special ballots cast during the 2019 election, but nowhere near the estimated two million to five million the agency had been braced to handle this time in the midst of the COVID-19 pandemic.

Canadians have until Sept. 14 to apply for a special ballot so the number could yet increase dramatically.

"The important thing for us is to be prepared. We planned for high volumes to be sure we would be ready," said Elections Canada spokesman Matthew McKenna.

"We still believe that voting in person during advance polls or on election day is the simplest, most efficient way to cast a ballot in this election, and we expect the majority of Canadians will choose one of these options."

Elections Canada is updating the number of special ballots issued and returned daily on its website.

Not all of them are destined to be mailed in. Some will be dropped off at Elections Canada offices.

Of the special ballots issued as of Wednesday evening, 282,576 had been provided to electors living in Canada and intending to vote in their ridings, either by mail or at their local Elections Canada office.

Of those, 45,282 had been returned. Elections Canada is not able to say how many returned ballots were mailed versus dropped off at one of its offices.

Another 18,733 special ballots had been issued to electors who are in Canada, but outside their ridings and intending to vote by mail or at an Elections Canada office. None of those had been returned as of Wednesday.

As well, 43,347 had been issued to Canadians living outside the country. None of those had been returned either.

Theoretically, a massive volume of mail-in ballots could have an impact on the election outcome. For instance, if millions of electors were to vote well in advance of Sept. 20, that could make it harder for a party to capitalize on a late surge in support or recover from an early plunge in popularity.

Parties have adjusted their campaign strategies somewhat as a result. The NDP, for instance, released their platform a few days before the election was actually called, partly in a bid to ensure that any early mail-in voters would have all the information needed to make their choices.

The Conservatives released their platform the day after the election call, whereas the Liberals have stuck with a more traditional timetable, releasing their platform Wednesday at the mid-point of the campaign.

Traditionally, parties urge their rock-ribbed supporters to vote in advance polls, leaving their campaigns free to concentrate election day get-out-the-vote efforts on likely supporters who don't make up their minds until the bitter end.

This time, the NDP is encouraging supporters to apply for mail-in ballots. The party has even created its own website to help voters figure out how to do that.

Liberals are similarly flogging the mail-in option but also encouraging their supporters to go to their local Elections Canada offices, where they can fill out a special ballot on the spot and drop it off immediately -- locking in those votes securely well ahead of election day.

Cristine de Clercy, co-director of the leadership and democracy laboratory at Western University, said it makes more sense than usual for parties to get their committed supporters to vote as early as possible.

Given the unpredictable course of the pandemic, even conscientious electors who fully intended to cast ballots in person could decide it's too risky come Sept. 20, she notes.

"If I were a party strategist, the first thing I would be telling all of my candidates is, 'Get your partisans to vote by mail, right now," she said.

In last fall's U.S. presidential election, Democrats disproportionately voted by mail while Republicans were actively discouraged from doing so, in line with former president Donald Trump's baseless claims that the process would lead to a rigged election. Consequently, a number of states flipped to the Democrats when the mail-in ballots were counted, handing victory to Joe Biden.

There is no similar ideological or partisan divide over mail-in voting in Canada, where all parties support the wisdom of giving voters the option.

Still, University of British Columbia political scientist Richard Johnston says New Democrats tended to disproportionately take advantage of the mail-in option during his province's election last fall.

In that case, John Horgan's NDP was assured a majority on election day but picked up four more tightly contested seats once the mail-in ballots were counted.

Since mail-in voting is an option for people who are worried about the threat of COVID-19, Johnston says it's possible federally that Liberal and NDP supporters will use it more than Conservative supporters, whom polls suggest tend to be less concerned about the risk.

That said, Johnston is doubtful mail-in voting will be as widely used in the federal election as it was in B.C. -- largely because about 75 per cent of eligible Canadians are fully vaccinated now and may feel less wary about voting in person.

"Certainly, the feel of society does not suggest that there will be quite the stampede to mail-in voting that there was in previous times," he said.

Consequently, Johnston added: "I would think parties would be unwise to certainly motivate their strategies and their logistics all that dramatically because of the possibility of mail-in ballots. They still need to get millions of voters down toward the end of the campaign."

Young people are the one demographic where some parties might want to direct their efforts to encourage mail-in voting.

Due to the pandemic, Elections Canada is not offering the option of campus voting this time for university and college students who aren't able to vote in their home ridings.

"It seems to me that this election may well disadvantage young voters who tend to turn out a little bit more enthusiastically for the Liberals and the NDP," said de Clercy.

She's skeptical that mail-in voting will prove to be a realistic option for students, many of whom are first-time voters who'll have to familiarize themselves with the special ballot process by Sept. 14, just as they're moving and settling in to a new school year -- "which is asking a lot when you're moving around."

De Clercy suspects mail-in voters will be "loaded towards a specific demographic" -- likely older, upper income, higher education.

"That's obviously a concern because, of course, in a democracy you want everybody who can vote to vote."

This report by The Canadian Press was first published Sept. 1, 2021.