The campaigning for two seats up for grabs in the provincial legislature didn’t let up on the holiday weekend, as candidates and their parties continued to press the public for support in the final days before a pair of byelections.

Ontarians living in the provincial ridings of Kitchener-Waterloo and Vaughan will head to the polls Thursday to cast ballots in the two crucial byelections, which could potentially deliver a majority for the governing Liberals.

If the Liberals manage to win both seats, they will regain the majority control of the legislature they held during Dalton McGuinty’s first two terms as premier.

If they can’t win them both, it will not substantially change the character of the legislature, as neither opposition party will be able to take control with the addition of just a single seat or two.

But without a victory in both ridings, the Liberal government will be forced to live with the threat of a snap election hanging over its head for the fall session, just as it has done in the months that have passed since the provincial election in October of last year.

Jonah Schein, the MPP for the Toronto riding of Davenport, tweeted Monday that he was en route to "knock on doors" in Kitchener-Waterloo, in support of Catherine Fife, a school board chair representing the New Democrats.

While campaigning on Labour Day, Fife herself was joined for a time by provincial NDP Leader Andrea Horwath and Tom Mulcair, the leader of the federal New Democrats.

The federal NDP leader said Horwath and her party had "shown that politics can be done differently," endorsing both the Ontario leader and the Kitchener-Waterloo candidate.

Fife said voters in Kitchener-Waterloo are "ready for a change" and asked them to support the New Democrats.

Tories urge voters to choose 'better path'

The Official Opposition, meanwhile, posted a video Monday from Progressive Conservative Leader Tim Hudak, which called on Ontarians to support his party in the upcoming byelections.

"Send a message that we need change in Ontario to a better path," Hudak said in a message that was posted to YouTube on Monday.

The Progressive Conservative candidate, Tracey Weiler, was taking a similar message to voters on the campaign trail in recent days, telling CBC News that "we do not want to give the Liberal government the majority that they've asked for."

Eric Davis, a lawyer, is running for the Liberals in the tightly contested race, just as he did in the previous general election when he lost to the Progressive Conservative incumbent.

"Kitchener-Waterloo voters are moderate and progressive and I plan to represent those values," Davis said recently.

The southwestern Ontario riding of Kitchener-Waterloo was previously held by the Progressive Conservatives for six straight elections.

It was vacated earlier this year when long-time MPP Elizabeth Witmer stepped down to take a job with the Workplace Safety and Insurance Board.

'Anything could happen'

This time around, the Kitchener-Waterloo race is too close to call, said political scientist Brian Tanguay.

"Really, on Election Day, anything could happen," Tanguay told CBC News in a recent interview.

The uncertainty surrounding the election race explains the frequent appearances that party leaders have made in the riding during the campaign.

McGuinty has been to Kitchener-Waterloo twice in recent days, Horwath has visited at least 10 times in the past month and Hudak has made 11 appearances since the Progressive Conservative candidate was named.

Just north of Toronto, campaigning also continues in Vaughan.

That riding opened up when Greg Sorbara announced his resignation, citing an intention to spend more time with his family and on his private business interests.

His former assistant, Steven Del Duca, is now running for his seat.

Del Duca is up against Progressive Conservative candidate Tony Genco and Paul Donofrio, the candidate for the New Democrats — both of whom were defeated by Sorbara in the October 2011 election.

With files from the CBC's Mike Crawley