“Until now there has been very little cooperation between these two blocs,” Mr. Larsson said. He said that although the government appeared to be weak and unstable, it was likely to survive for a full, four-year term.
But voices on the right and the left were highly critical of the deal.
“The Center Party and the Liberals have been duped,” said Ulf Kristersson, leader of the Moderate Party, referring to private assurances that Mr. Lofven made to the Left Party. He and Ebba Busch Thor, the leader of the other member of last year’s four-party bloc, the Christian Democrats, declared the alliance dead.
Ms. Busch Thor called the new arrangement “an unholy alliance.”
Former Prime Minister Carl Bildt, a moderate, wrote on Twitter: “After some sort of secret supplementary agreement with the ex-Communists PM Löfven will be back as PM in Sweden again. And with policies leaning in the other direction. Messy arrangement.”
“A historic mistake,” a former Left Party politician, Rossana Dinamarca, said on Twitter. “They have let in a Social Democrat-led right-wing government without getting anything in return.”
On Thursday, three longtime Green politicians left the party in protest. One of them, Carl Schlyter, told the public broadcaster SVT that the left bloc would have been more effective in the opposition than peddling a conservative agenda.
“People who are struggling have very few places to turn in this agreement,” he said.
Daniel Suhonen, the head of Katalys, a trade union research group, said the mix of free-market policies, weakened worker protections and potentially relaxed migration rules could backfire in favor of the Sweden Democrats.