The Swedish Election Authority explained in a press release that an unusually large number of overseas votes and the late delivery of many early votes to polling stations had delayed the vote count, meaning it will not be completed until Thursday.
"We are expecting a greater number of votes this year than in previous elections. We can't know the number in advance, but we estimate that we're talking about close to 300,000 votes in this year's election," said Anna Nyqvist, head of the Swedish Election Authority’s administrative office.
"This means that the cumulative count will probably take a long time in many municipalities and that we will not have a preliminary updated result for the parliamentary election until Thursday."
In Swedish elections, the election board, or valnämnden, in each municipality has full responsibility for handling voting and vote-counting. The boards are also responsible for the so-called onsdagsrösterna, or Wednesday votes, the early and overseas votes that could not be counted on election night.
Rather than being counted at individual polling stations, these are counted in 314 aggregate uppsamlingsdistrikt, or "collection districts" with the finished vote than passed to the County administrative boards, or länsstyrelserna for checking.
As the count stands at present, the four opposition parties have 176 seats while the Tidö parties backing the current government have 173.
Gustav Karreskog Rehbinder, the mathematician who founded Vera Policy, which public broadcaster SVT used for its election night forecast, said that while one side might get an extra seat, it was unlikely that the votes counted on Wednesday and Thursday would deliver the two seats needed for a Tidö victory.
"That last seat, whether it will be 176 or 175 for the red-green parties, is pretty uncertain. The seat can jump around a bit during the count and could end up with the Left Party, the Social Democrats or the Moderates," he told TV4. "However, it is unlikely that it will go all the way to the Tidö sides winning and picking up two additional seats. If nothing unexpected happens, the opposition are going to bring this home."