Outgoing Swedish Prime Minister Stefan Löfven has been tasked with forming a new government after the conservative party gave up on hopes of a majority.
The opposition Moderate Party leader Ulf Kristersson confirmed that he had failed to find a majority to support his bid for Prime Minister.
The task then falls once again to Löfven's Social Democrat party -- Sweden's largest political group -- just days after he resigned from his post.
"The parliamentary conditions for forming a new right-wing government are simply not there," Kristersson told a news conference on Thursday.
The Moderate party had been tasked with forming a government on Tuesday after an initial round of talks with party leaders.
The Swedish parliamentary speaker Andreas Norlén, himself a member of the Moderates, had given the party three days to find support.
But after's Kristersson failure, Norlén announced that he would now entrust the task to the caretaker PM Löfven, who has until Monday to find a majority.
Löfven chose to resign rather than hold early elections, after losing a historic vote of confidence last week.
It is not the first time that Sweden has been embroiled in political uncertainty. After the 2018 parliamentary elections, it took four months of negotiations before Löfven was reappointed as Prime Minister in January 2019.
Norlén has argued that the process "could not take as long" this time. If no majority is formed after four attempts, early elections will be called in Sweden within three months. Sweden has not held an early election since 1958.
In order to become Prime Minister, a candidate must not be rejected by an absolute majority of 175 members.