STOCKHOLM (Reuters) - Sweden's center-left opposition leads the field ahead of Sunday's general election, but a poll on Saturday pointed to a narrow victory and a complex task in building a stable government after the vote.
The Sifo poll gave the three center-left opposition parties a lead of 5.7 percentage points over the ruling center-right government. In the previous Sifo survey on Sept. 10, the gap between the two blocs was 6.2 percentage points.
Polls show voters are tired of a four-party Alliance coalition that has slashed taxes by more than 130 billion crowns ($18.25 billion) over the last 8 years, but is blamed for weakening the cradle-to-grave welfare state.
A split opposition of the Social Democrats, Greens and Left parties, however, has failed to capitalize on those concerns, despite promising more spending on healthcare and schools.
With the Social Democrats - the largest opposition party - looking like winning around 30 percent of the vote, union leader turned prime minister-in-waiting Stefan Lofven could struggle to cobble together a stable administration.
"Just now, it looks more and more like there will be a change of government," said Magnus Hagevi, associate professor of political science at Linnaeus University.
The Social Democrats are fighting the election alone and have been coy about which parties they would govern with if - as looks certain - they don't get a majority.
"The current situation points to a very complex process to form a government," Hagevi said.
Lofven has said the Greens are a "natural partner", but together the two parties could be smaller than the current center-right government.
Bringing the Left Party into government or getting the backing of its leader Jonas Sjostedt, is an alternative. But that could still leave the center-left short of a majority in parliament if the anti-immigration Sweden Democrats were to side with the Alliance.
The poll showed the Sweden Democrats with 10.3 percent of the vote, making them the country's third-largest party after the Social Democrats and the Moderates of Prime Minister Fredrik Reinfeldt.
Both the center-right and center-left have said they will not cooperate with a party that wants a 90 percent cut in the number of asylum seekers Sweden takes in.
Widely admired for its strong economy, stable government and liberal attitude to immigration, Sweden nevertheless faces significant challenges which a weak government will struggle to deal with.
Unemployment is high, particularly among immigrants and young people, and a housing bubble threatens economic stability. The rise of the far-right indicates a society starting to question its role as what PM Reinfeldt call "a humanitarian superpower."
Saturday's poll, commissioned by daily Svenska Dagbladet showed the center-left with 45.7 percent support against 40.0 percent for the Alliance government.
Feminist Initiative, a left wing party, got 3.0 percent.
Should the feminist party pass 4 percent, the threshold to enter parliament, it would support the Social Democrats, strengthening a Lofven government and potentially giving him a majority.
But it would also push the Social Democrats further to the left, making it harder to bring in parties from the Alliance, as Stefan Lofven has said he would like to do, in the event the Sweden Democrats hold the balance of power.
If the election result were to reflect the poll, the Social Democrats, the Greens and Left parties would hold more seats in parliament than the current government, but not an outright majority of 175 seats or more.
(Reporting by Anna Ringstrom; Editing by Tom Heneghan)