Oslo/Stockholm  - The future government in Norway faces several tough decisions including the size of welfare expenditure and whether oil and gas drilling should be allowed in sensitive areas off the north-western coast.

Over 3.5 million Norwegians are eligible to vote in the polls on Monday (September 14) to decide the composition of the 169-seat parliament.

The red-green coalition headed by Prime Minister Jens Stoltenberg's Labour Party is seeking a new four-year term, but according to recent opinion polls will lose its majority.

Stoltenberg, 50, wrote political history in 2005 when his party agreed to share power with the Centre Party and Socialist Left Party, rather than form a minority government.

The coalition won 87 seats, and the Socialist Left Party leader became finance minister.

Should the red-greens be voted out of office, there is uncertainty over who will succeed Stoltenberg as premier.

"The others do not have a clear alternative," has been Stoltenberg's message on the campaign trail.

The four non-socialist parties - the Christian Democrats, the Liberals, the Conservatives and the Progress Party - have been unable to agree on an alliance or joint platform.

Rather, the leaders of the four parties have made statements and issued "guarantees" to voters on specific issues they would refuse to compromise on, suggesting deep divides and difficult talks ahead.

The Christian Democrats and the Liberal Party - together polling some 11 per cent of the vote - have said they will not join a government headed by the populist Progress Party that won 38 seats in the outgoing legislature.

Liberal Party leader Lars Sponheim says he would not even give parliamentary backing to a populist-led government, citing differences over Jensen's calls for tighter rules on immigration and big tax cuts.

Progress Party leader Siv Jensen, 40, has fired back, saying it is "unreasonable" to shut out a party that accounts for half of the seats among the non-socialists and that her party will not simply accept being a passive supporter.

The elections are Jensen's first since she in 2007 took over at the helm from veteran Carl I Hagen.

Conservative Party leader Erna Solberg has emerged as a possible alternative to Stoltenberg, and she has kept her options open - indicating she is willing to "talk" with the other three party leaders.

Solberg is open for oil-drilling in pristine sea areas off Lofoten and the surrounding archipelago in northern Norway, a stance the Liberals oppose.

"The business sector needs this expansion," Solberg said on public broadcaster NRK, adding that possible talks with future government partners will be "tough".

Stoltenberg's coalition partners have earlier agreed to disagree on that matter, though the Labour Party is more inclined to go ahead with exploration.

Looming in the background is the contentious issue of Norway's possible membership the European Union. Voters have in two referendums, 1972 and 1994, rejected joining the bloc.

Changes planned in the EU's decision-making - should the Lisbon Treaty be adopted - and ongoing enlargement may trigger calls for a new debate.

Though personally in favour of Norwegian membership, Foreign Minister Jonas Gahr Store recently said "there is no political climate for a Norwegian debate on EU membership." (dpa)