OTTAWA, April 28 (Xinhua) -- Millions of Canadians are lining up to cast their ballots on Monday as U.S. President Donald Trump weighed in on the election with a new threat of annexation of the country.

According to Elections Canada, there are 28,525,638 registered electors without those who registered on election day. Around 7.3 million electors voted on the four advance polling days.

The agency said it will publish the preliminary results as the first polls close in the country on Monday and the first results will be available shortly after 7:00 p.m. (EST).

Trump posted on social media on Monday that Canada could become a 51st U.S. state without "an artificially drawn line from many years ago."

Trump's repeated threats about Canadian sovereignty, along with the tariffs imposed on the country, became key issues in the 36-day campaign.

Nanos Research said 2025 was a seismic period in federal politics: the year opened with the Conservatives at 47 percent support followed by the Liberals at a 20 percent on the eve of Justin Trudeau's resignation.

According to the final tracking conducted by Nanos Research on Sunday, the Liberals were at 42.6 percent, with a 2.7-point advantage over the Conservatives. As to who Canadians would prefer as Prime Minister, Liberal Leader Mark Carney came in at 51.9 percent, followed by Conservative Leader Pierre Poilievre at 32.1 percent.