Swedish Prime Minister Ulf Kristersson has resigned after his right-wing governing bloc narrowly lost the general election to the centre-left opposition. The result is expected to return Social Democrat leader Magdalena Andersson to power, although forming a government may be difficult because the opposition parties disagree on issues including taxation.

Preliminary results indicate the opposition will win 176 of the Riksdag’s 349 seats, compared with 173 for Kristersson’s bloc, a margin of roughly 50,000 votes in a country of 10 million people. The results still require formal certification, while late and overseas ballots are being counted; Sweden’s next government could take weeks or months to form, as happened after previous elections.