- Change is in the air -

Barring a major upset, Prime Minister Erna Solberg's centre-right coalition that has governed Norway since 2013 is set to be ousted, according to opinion polls and experts.

Labour Party leader Jonas Gahr Store is instead poised to win the polls.

Whether he will be able to form a coalition of left-leaning and green parties, with a majority, is another question.

- Veteran v. millionaire -

No other Conservative leader has governed Norway as long as Solberg, nicknamed "Iron Erna."

A native of the western city of Bergen, the 60-year-old steered the country through successive crises from the migrant wave in 2015 to plunging oil prices and the Covid-19 pandemic.

Store, 61, is a millionaire whose main campaign plank is the fight against inequality.

A graduate of Sciences Po in Paris, he follows in the footsteps of his mentor and friend Jens Stoltenberg, the current NATO secretary general. Store served as foreign minister and then health minister in Stoltenberg's governments.

He failed to oust Solberg in the 2017 election.

- Climate crisis -

The UN's alarming climate report in August has propelled global warming to the heart of the election campaign, with a focus on the future of the oil industry in western Europe's biggest producer.

Several parties on both sides -- the Greens, Socialist Left and Liberals -- want to put an end to the oil industry and ban any further prospecting.

Their ability to make any inroads on the issue with the bigger parties -- which are more favourable to the industry -- will depend on their election scores and the balance of power.

- Splintered political landscape -

Norway's splintered political landscape makes coalition-building difficult.

The two biggest parties, Labour and the Conservatives, have seen their voter bases decline with the rise of smaller parties.

On the left, five parties are in agreement to oust the current government, but some of these have diametrically opposed positions and have said they will not govern together.

If Store is unable to build a coalition with a majority, he could choose to govern solo in a minority government and get backing on a case-by-case basis to pass legislation.

On the right, things are not much different.

The Conservatives are supported by a clutch of smaller parties, which also have their own disagreements.

- The magical number 4 -

Much will depend on the small parties' election night score. Several of them are hovering around the four percent level.

Under the Norwegian system, parties that get more than four percent qualify for the 19 so-called "levelling seats" in the 169-seat parliament, which often prove crucial for building a majority.