A clutch of close-run ridings, including a nail-biting photo finish in Vancouver Granville, are still waiting for mail ballots to be counted to determine the final result.
But Elections Canada says it expects most of the 850,000 postal votes that were not counted by Monday night to be tallied by the end of Wednesday.
Three new ridings that were still too close to call on election night — Fredericton, Northwest Territories and Yukon — have now been declared for the Liberals after the count wrapped up.
But in a number of knife-edge races, candidates are holding their breath to see if mail ballots confirm the results of in-person votes.
In Edmonton Griesbach, where The Canadian Press is projecting Blake Desjarlais delivered a notable victory for the NDP over the Conservatives — mail ballots are still being counted.
Some 1,660 ballots were still being counted on Wednesday in one of the tightest races of the election in Sault Ste. Marie, Ont. A mere 30 votes separate Liberal incumbent Terry Sheehan from Conservative Sonny Spina.
Elections Canada has warned that in some ridings with thousands of ballots final results may not be available until Friday.
In some constituencies, verifying mail ballots took all day Tuesday, before counting could start, a spokesman for Elections Canada said.
Mail ballots have to be carefully checked to ensure they have been signed and that people have not already voted in person, or sent in more than one ballot by post.
In ridings facing a photo finish, candidates are likely to ask for a recount, which could further delay the result.
But it is the close-run battles where mail ballots could dictate who wins and who misses out.
In Nanaimo-Ladysmith, 989 votes separate New Democrat Lisa Marie Barron from Conservative Tamara Kronis. On Wednesday, 6,892 postal votes were still being counted.
In Richmond Centre, 691 votes separate Liberal Wilson Miao from Conservative incumbent Alice Wong. But there are 4,463 mail ballots which could determine the final result in the marginal riding.
British Columbia received the most mail ballots of all the provinces.
In Victoria, more than 12,600 people voted by mail, the most in Canada, followed by Saanich-Gulf Islands where over 10,700 people opted for postal votes.
Matthew McKenna, a spokesman for Elections Canada, said verifying huge numbers of ballots had delayed counting in some areas.
"The counting of local ballots will take place throughout the day — local offices also had to do verifications of special ballots, and for many, that took all day yesterday, and may still be going," he said Wednesday. "We do expect the vast majority to be counted by the end of the day."