By Johan Sennero and Simon Johnson
STOCKHOLM (Reuters) - Swedish Social Democrats leader and caretaker Prime Minister Stefan Lofven was handed the task on Monday of forming a new government with sufficient support in a parliament left deeply divided following last month's inconclusive elections.
But his prospects, like those of his main rival, Alliance bloc leader Ulf Kristersson, look bleak.
The election on Sept. 9 delivered a hung parliament with the anti-immigration Sweden Democrats holding the balance of power, although neither the centre left nor centre-right bloc is willing to do a deal with them.
"This will demand hard and probably also protracted work," Lofven told a news conference.
"I am not going to stoke expectations for a quick solution, rather the opposite. It is obvious that many roadblocks remain."
Moderate Party leader Kristersson, the Alliance's candidate for prime minister, had a first stab at forming a government but failed and Lofven acknowledged that his own efforts would probably face similar obstacles.
The Centre and Liberal parties that Lofven will primarily be looking to win over are reluctant to abandon the centre-right Alliance bloc and both said they still hoped to see Kristersson as prime minister with bipartisan support.
Lofven has ruled out supporting the centre right unless they agree to keep him on as prime minister.
"The parties have to rethink where they stand if we are going to get further in this process," Speaker Andreas Norlen said as he announced that Lofven would be given the task of sounding out possibilities to form a government.
Lofven lost a vote of no-confidence as prime minister on Sept. 25.
His centre-left bloc of the Social Democrats, Greens and Left party has 144 seats in the 349-member parliament, one more than the centre-right Alliance. The Sweden Democrats, with roots in the white supremacist fringe, have 62 seats.
The Centre and Liberal parties scuppered Kristersson's attempt at forming a government over the weekend, saying his proposals would leave the government needing support from the Sweden Democrats.
Although united in their determination to keep the Sweden Democrats isolated, the Centre and Liberal parties champion economic policies that put them considerably to the right of Lofven's Social Democrats, who have ruled over the past four years with the backing of the former Communist Left Party.
Graphic: Swedish election scenarios: https://tmsnrt.rs/2p45tJh
(Additional reporting by Daniel Dickson; editing by Niklas Pollard and Ed Osmond)