STOCKHOLM - Sweden is heading for a tight general election on Sunday, with polls showing Prime Minister Magdalena Andersson neck and neck with the opposition that is looking to unseat her Social Democrats.

The vote comes after a campaign dominated by skyrocketing electricity prices and soaring gun violence that are shaking Swedish society to the core. The country, long a bastion of social democracy, has seen its political landscape upended by the nationalist Sweden Democrats over the past years.

The anti-immigration party is a part of the centre-right opposition bloc that is seeking four years at the helm of the biggest Nordic country, proposing to reverse a policy of gradually exiting nuclear energy and warning Ms Andersson's victory could result in higher taxes. Still, she could benefit from being seen as a responsible leader in time of crisis.

The results will trickle in on Sunday night and by Monday morning it should be clear whether opposition parties will get a shot at forming a new government. Those talks are likely to become drawn-out and complicated regardless of the winner, given larger parties need to appease smaller ones to govern.

Under Sweden's Constitution, a government does not need backing from a majority in the 349-seat Parliament, but it will need to avoid having a majority vote against it, which means passive support through abstentions can be key.

Here is what you need to know ahead of the vote.

Who are the main rivals?

Ms Andersson, 55, is Sweden's first female prime minister. She leads the current Social Democratic government and is gunning for another term in office helped by three smaller parties that have named her their preferred candidate.

She has enjoyed high approval ratings since taking her position in November last year, showing pragmatism as she backed Sweden's momentous decision to apply for membership in defence alliance Nato in the wake of Russia's full-scale invasion of Ukraine.

As voters tend to stick with the incumbent at a time of crisis, she could benefit from a "rally round the flag" effect.

On the right side of the spectrum, opposition parties have coalesced around Moderate Party leader Ulf Kristersson, 58, to form a loose coalition that aims to replace Ms Andersson.

His party has made support for nuclear power a key tenet of its election campaign. It has also warned that Swedes' tax burden could increase under Ms Andersson, who has suggested that an expansion of the country's defence might be financed by increasing tax rates for top earners.

Mr Kristersson also needs to watch his back. He is working with the Sweden Democrats, who are currently polling ahead of his Moderates.

The nationalist party, led by Mr Jimmie Akesson, used to be universally shunned for its far-right and neo-Nazi roots, but has become more palatable after seeking to weed out extremists and abandoning some controversial policies, such as a demand for Sweden to leave the European Union.

While Mr Kristersson has accepted that Mr Akesson's backing is the Moderates' best shot at gaining the premiership, he will also need the support of a smaller liberal party that wants to keep the Sweden Democrats as far away as possible from power.

What do the polls indicate?

The surveys indicate a margin so slim that it is impossible to predict which side ends up controlling the 175 seats needed for a majority in Parliament. The camps are neck-and-neck, at 49.6 per cent for the ruling Social Democrats and 49.4 per cent for the opposition bloc.

For Ms Andersson's Social Democrats, that figure includes parties that could support her, actively or passively. On the right, Sweden Democrats poll at 21.2 per cent, with the Moderates trailing the nationalists at 17.2 per cent, in the latest reading at pollofpolls.se, which combines the results from seven pollsters.

That is giving smaller parties a crucial role: the Green Party and the Liberals will each have to pass a 4 per cent threshold to even get into the Parliament to play a supporting role for Ms Andersson and Mr Kristersson, respectively. The Greens currently poll at 5.5 per cent, while the Liberals are backed by 4.9 per cent.

What are the top issues?

Swedish voters normally prioritise healthcare, education and immigration. This time, those topics have largely been overshadowed by energy and crime as campaigns neared the finish line.

Soaring electricity prices and Ms Andersson's warning of a coming "war winter" put energy on voters minds. Given energy policy is traditionally a vote-winner for the Moderates and their allies, the Social Democrats have tried to take the initiative by proposing an extensive compensation plan to help out consumers.

A surge in gang-related gun violence that has claimed hundreds of lives in recent years has made issues around law and order a key priority for voters with the government criticised for failures in integrating tens of thousands of immigrants.

According to conventional wisdom, crime on the agenda should also favour right-of-centre parties, but polls suggest that only the Sweden Democrats, who have built their success on a strict anti-immigration stance, have benefited.

What could a new government look like?

If the left side wins, Ms Andersson is likely to remain prime minister, but she would still face a daunting task of crafting an agenda that her supporters could agree on. Parties that have said they would back her government span the gamut from former communists of the Left Party to the free-market Centre Party, which is dead set on keeping the leftists out of the Cabinet.

If the bloc of Mr Kristersson's Moderates wins, it remains unclear how the nationalists would act if they end up with more seats in Parliament than Mr Kristersson's party. They could demand to be part of the Cabinet, or make policy demands that would be difficult for the coalition's junior backer Liberals to stomach.

When will the picture become clearer?

After the 2018 election, it took four months for Ms Andersson's predecessor, Mr Stefan Lofven, to form a government as Sweden's traditional political blocs imploded following the emergence of the Sweden Democrats, which fragmented the electoral landscape.

Now that the political system has rearranged itself into looser blocs that include the nationalist party and all parties have declared their preferred candidate to lead a new government, there may be scope for a quicker deal, though pundits are still bracing for some tough wrangling. BLOOMBERG