Norway is holding parliamentary elections that could land the anti-immigration Progress Party in government and lead to a change of power for the first time since 2005.
Despite Norway's strong economy and low unemployment, Prime Minister Jens Stoltenberg's ruling, centre-left coalition has been trailing in opinion polls for months ahead of election day.
The Progress Party appears likely to come into power for the first time as part of a centre-right coalition led by Erna Solberg's Conservative Party.
It is the first parliamentary election since the 2011 massacre when Anders Behring Breivik killed 77 people. Thirty-three survivors of the attack on Utoya island, mostly teenage members of the Labor Party youth wing, are seeking national office in the election.
One political expert said Mr Stoltenberg's main challenge was simply the fact that he had been in power for so long.
"I call it government fatigue. The Labor coalition has been in power for eight years and one would expect that some voters now think it is time for a change," said Frank Aarebrot, professor of comparative politics at the University of Bergen.
Mr Stoltenberg was admired for his calm demeanour after Breivik's attacks and support for his Labor Party saw a short-lived boost. But last year a report criticising Norwegian police for a litany of institutional failures before and during the attacks dented his government's prestige.