Neither of the two mainstream blocs can form a government on their own as far-right party makes major gains

Sweden faced political deadlock on Monday after the far-right made gains in legislative elections that left the question of who will form the next government up in the air.

As expected, neither Social Democratic Prime Minister Stefan Lofven’s centre-left bloc nor the centre-right Opposition garnered a majority.

Third-biggest party

The far-right Sweden Democrats, with roots in the neo-Nazi movement, solidified their position as third-biggest party, though they have yet to shake their outcast status.

“However the dramatic bloc battle plays out, it looks like it will be difficult for Sweden to have a functioning government,” paper of reference Dagens Nyheter predicted.

Mr. Lofven met Monday with his party leadership to map out his road ahead.

Parliamentary group leader Anders Ygeman said “it could take weeks, maybe even months” before Sweden had a government in place.

Mr. Lofven’s bloc enjoys a razor-thin one-seat lead over the Opposition Alliance.

The Social Democrats won 28.4% of votes, down 2.8 points from the 2014 elections, their worst score in a century. “Nevertheless, voters made the Social Democrats Sweden’s biggest party,” Mr. Lofven said.

He has extended an invitation to the opposition in a bid to break the deadlock.

“We need a cross-bloc cooperation,” he told party supporters on Sunday evening.

The four-party Alliance has however rejected his offer, urging him to step down and make way for them to form a government.

New mandate

Mr. Lofven is seeking a new four-year mandate but he will have difficulty setting up a stable government. He, like all of the other parties, has ruled out any cooperation with the far-right. He could try to build a similar government to 2014: a minority coalition with the Greens that relies on informal support in parliament from the ex-communist Left Party. But it would then be under constant threat from the Sweden Democrats, out to topple it at the first opportunity.

They are ready to block any attempt to pass legislation, such as the autumn budget bill.

Mr. Lofven could also invite the Centre and Liberal parties to join him at the negotiating table.

With one major caveat: the Centre and Liberals are members of the Alliance, together with the Moderates and Christian Democrats.

Despite their differences, notably on immigration policy, the Alliance parties that ruled Sweden from 2006 to 2014 have agreed to try to form a government together.

But that is no easy task.