IT WAS supposed to be the Swedish Social Democrats’ triumphant return. But two months after forming a minority coalition government with the Greens, Stefan Lofven, the Social Democratic leader, has been forced to step down as prime minister. The four-party centre-right opposition alliance enlisted the support of the far-right, anti-immigrant Sweden Democrats to vote down his budget, pushing through a budget of its own instead. Mr Lofven might have let the other parties try to form a new government. But instead he plans to call an “extra” election on March 22nd.Such high political drama is rare in Sweden, where advance negotiations before parliamentary votes normally mean the budget passes with little fuss. The only previous special election was in 1958. Social Democratic-led governments, in particular, have usually sat out their four-year terms in an orderly fashion.But Sweden has never before had to contend with a far-right party that enjoys as much support as the Sweden Democrats. The party is the third-largest in parliament. Without its backing, neither the centre-right alliance nor a coalition of the Social Democrats, Greens and the small Left party commands a majority. Worse, a new election could see the Sweden Democrats grow stronger, although the absence on sick leave of their leader, Jimmie Akesson, may count against them. The Sweden Democrats say they blocked the…