Unlock stock picks and a broker-level newsfeed that powers Wall Street.
EXPLAINER-Tough talks beckon for winner in Sweden's close-run election

* Swedish general elections on Sept. 11

* Centre-left and right-wing blocs running neck-and-neck

* Social Dems, Moderates leaders contenders for PM

* Either side face tough negotiations to form government

By Niklas Pollard

STOCKHOLM, Sept 6 (Reuters) - Tough talks and trade-offs await the winning side in Sweden's parliamentary elections with the governing centre-left and their right-wing challengers facing weeks of uncertainty should they come out on top.

Opinion polls ahead of the Sept. 11 vote show Social Democrat Magdalena Andersson and her allies running neck-and-neck with a right-wing bloc where Ulf Kristersson, leader of the conservative Moderates, is the main candidate to unseat her as prime minister.

Below is an explainer on the elections and the process to form a government.

WHO ARE THE CONTENDERS?

Andersson, the first woman to become Swedish prime minister after Stefan Lofven unexpectedly stepped down last year, is more popular than her own party and the political leader most trusted among voters, opinion polls show https://demoskop.se/news/partiledarfortroende-augusti-2022.

Still, the four-party centre-left bloc that would favour her as prime minister is only loosely aligned, even if the Social Democrats are by far the biggest player.

Meanwhile, their allies the Greens have been polling dangerously close to the 4% threshold to win Riksdag seats, as have the right's Liberals, adding uncertainty.

On the right, Kristersson's Moderates are vying with the anti-immigration populists of the Sweden Democrats to be the biggest party of that bloc.

Recent polls show the Sweden Democrats running ahead of the Moderates, raising doubts about Kristersson's plans to become prime minister in coalition with the Christian Democrats, but with Sweden Democrat and Liberal support in parliament.

Kristersson, a career politician for years eclipsed by former Prime Minister Fredrik Reinfeldt, who championed a more centrist and pro-immigration agenda, has said he is the only leader capable of uniting the right.

"It won't be easy, but it is totally doable," Kristersson told Reuters on the campaign trail in Gothenburg. "We are already sitting down together and we can talk to each other."

Yet the strong support for Jimmie Akesson's Sweden Democrats, founded decades ago in part by activists with neo-Nazi and white supremacist links, make them increasingly hard to ignore when considering a right-wing government.

WHAT ARE THE MAIN ISSUES?

Gang violence, with shootings spreading out of the main cities, has taken centre stage in the campaign with all sides pledging to further tighten legislation and expand the police force.