Sweden’s centre-left government resigned on Monday but prime minister Stefan Lofven declined to call snap elections, saying he would try to form a new coalition to break a parliamentary gridlock caused by the rise of a nationalist party.

“With one year left until regular elections, and with regards to the extraordinary situation that the country finds itself in with the ongoing pandemic with the special challenges that would involve, snap elections are not what is best for Sweden,” Lofven told a press conference on Monday.

He said the decision to resign had been “the toughest” he had ever had to take.

The prime minister’s resignation means that the speaker of Sweden’s parliament now has four attempts to try to find a new government. Sweden’s traditional left-right politics have been shaken by the emergence of the nationalist Sweden Democrats, who first entered parliament in 2010 and now are the third-largest party.

Political experts say it is far from certain that a new government can be formed. Lofven took four months in 2018 to form a minority coalition between his Social Democrats and the Greens, which was supported in parliament by two centre-right parties, Centre and the Liberals, as well as the ex-communist Left party.

The current political crisis was sparked by the Left party joining forces with the Sweden Democrats and other opposition groups, leading to the first successful no-confidence vote against a sitting Swedish prime minister.

The Centre party has said it is willing to negotiate with Lofven but not with the Left or Sweden Democrats. Centre has dropped its demand for reform of rent controls, the issue that led to Left voting against the government.

But the main centre-right opposition party, the Moderates, could struggle to form its own coalition as even with the support of the Sweden Democrats and the Liberals it is unlikely to gain a majority.

“Now the speaker of the parliament has to sound out alternative options, but there is no obvious way forward to a new government,” former centre-right prime minister Carl Bildt wrote on Twitter.

One possibility, used before in neighbouring Finland as well as Germany and Iceland, would be a grand coalition between the Social Democrats and centre-right parties.

Lofven told the Financial Times on Monday: “I have not excluded that. If the country enters a situation that requires it, then yes I’m open. But I can’t see it right now.”

He added that snap elections would take four months to organise and even then there was no guarantee they would give a clearer parliamentary picture. Given that two possible scenarios from health authorities are for an increase in Covid cases from August, Lofven said that it would be better to try to form a coalition from the current parliament first rather than “handing it over” to voters