Sweden's beleaguered Social Democratic Prime Minister Stefan Lofven said Sunday he would step down in November to allow a successor time to prepare for the country's September 2022 general election.

Lofven, who was reinstated as prime minister by parliament in early July just weeks after being ousted in a historic vote of no confidence, told a political rally he would "leave my position as party chairman at the party's congress in November and thereafter also resign as prime minister."

Lofven, 64, has served as party leader for almost 10 years and as prime minister since 2014.

"Everything has an end and I want to give my successor the best possible chances," he said.

The former welder and union leader has led a weak minority government together with the Greens Party for the past three years, struggling to find a workable coalition following inconclusive elections in September 2018.

The announcement of his resignation came nonetheless as a surprise, as Lofven had previously indicated he wanted to lead the party in the next election campaign.

But Ewa Stenberg, political commentator at Swedish daily Dagens Nyheter, said it was a wise decision on his part.

"Lofven's not a good election campaigner or debater, he's not the leader the Social Democrats need in a tough election campaign where rhetoric is important," she wrote.

"Against that background, it's logical that he hands over to someone who's better with words and who can spark enthusiasm."

It is not yet known who will succeed Lofven as party leader, though Stenberg speculated that Finance Minister Magdalena Andersson was a hot tip.

The person elected to succeed Lofven as party leader would have to be approved by parliament in order to take over as prime minister.