OSLO (AFP) - A rivalry between Norway's Labour Prime Minister Jens Stoltenberg and right-wing populist leader Siv Jensen has dominated the campaign for Monday's general election – but, ironically, both could end up knocked out of the race.

All attention has been focused on the leaders of Norway's two biggest parties for most of the lacklustre campaign, but they could wind up losing out following a massive push in recent days by Conservative Party leader Erna Solberg.

Stoltenberg has spent most of his life in politics, born March 16, 1959 into a wealthy family deeply entrenched in public service: his father Thorvald was one of Norway's top diplomats and a foreign minister, his mother Karin was to become a state secretary.

He spent part of his education in an experimental school, and as a teen he was close to Maoist circles opposed to NATO and the then European Community.

With his friends he stoned the US embassy in Oslo to protest against the Vietnam War.

After earning his economics degree, he won a seat in the Storting, or parliament, in 1991. He was later appointed energy minister and then finance minister, before becoming Norway's youngest ever prime minister in 2000, the day after his 41st birthday.

He stayed in the job for just 18 months, but that was long enough to carry out the partial privatisation of two heavyweights of the Norwegian economy, oil group Statoil and telecoms operator Telenor.

Slender and photogenic with his steel blue eyes and salt-and-pepper hair, Stoltenberg regained power in 2005, and can at the end of his four-year term now boast having steered his country through the global economic crisis with little damage done to its economy.

"He's happy in his job because there's no better place for him to combine his knowledge of economics, the hot topic of the moment, with his political convictions," his wife and mother of their two children, Ingrid Schulerud, told AFP.

His main rival, the bubbly Siv Jensen, has a very different background.

Born June 1, 1969 to a couple that owned a shoestore, she discovered politics around the age of 18 when she helped out her mother who had gotten involved as a volunteer after her divorce.

At the age of 28, Jensen was elected to parliament and took part in her first televised debate.

"I was so nervous that I was sick for hours. They had to come get me in the bathroom," she recalled.

With her blonde highlights and permanent suntan, she has become a veteran debater who commands the media's attention.

Single, opposed to feminism and to the omnipresence of the state in a country that cherishes gender equality and social democracy, Jensen took over the reins of the populist Progress Party in 2006.

Determined to make the party respectable yet retain its critical stance on what it calls the "sneak Islamisation" of Norwegian society, she has vowed to curb immigration and cut taxes, financed by dipping into the country's oil wealth stashed dutifully away for a rainy day.

"I consider myself a liberal. I can't wait to influence Norwegian politics in this direction," says Jensen, whose role model is former British prime minister Margaret Thatcher.

But the Progress Party remains too feisty for the centre-right, which has refused to collaborate with Jensen in a right-wing coalition that would also include the Conservatives.

That refusal could weaken the right-wing's chances of taking power, while opinion polls show the left-wing struggling to retain its majority.

That could open the door for the head of the Conservative Party, Erna Solberg, 48, who has undergone a makeover after being occasionally mocked in the media for her weight.

While she trails far behind in the polls, "Iron Erna" -- as she has been nicknamed since her stint as immigration minister in 2001 to 2005 -- hopes to take advantage of her position as a bridge-builder on the right wing.