Spain's ruling Socialists won general elections Sunday but may be just short of an absolute majority, exit polls showed, after a campaign focused on the slowing economy and rising immigration.

The polls on three Spanish television stations gave Prime Minister Jose Luis Rodriguez Zapatero's Socialist Party between 163 and 176 seats in the 350-member parliament against 145 and 152 for the conservative opposition Popular Party (PP) of Mariano Rajoy.

Official results are expected later Sunday.

The result could force the Socialists -- who were 12 seats short of an absolute majority in the previous legislature -- to again forge uncomfortable alliances with smaller regional nationalist parties to pass legislation.

"According to the first figures, there has been a high turnout, with a victory by the Socialist Party, the top party in terms of votes and seats," said Jose Blanco, the secretary general of the Socialist Party.

The PP's chief strategist, Pio Garcia Escudero, however, refused to concede defeat.

"Polls are only polls. The PP will achieve a magnificent result, probably a historic result," he said.

Spaniards voted in large numbers after a campaign cut short by the murder on Friday of a former municipal legislator by suspected Basque separatists.

As of 6:00 pm (1700 GMT), turnout was 61.09 percent, about two percentage points lower than at the same time in general elections four years ago but far higher than in 2000, the government said.

Analysts said a high turnout was crucial for Zapatero's re-election chances as Socialists supporters are seen as more prone to apathy than those of the PP.

The record participation in March 2004 helped Zapatero, now 47, to score a surprise win over Rajoy, 52, three days after train bombings in Madrid that killed 191 people.

Voters then were infuriated at the conservative government's insistence that ETA was to blame, even though evidence pointed to Islamic extremists angered by Madrid's role in the Iraq war.

After the election, Zapatero responded to popular opinion and withdrew the country's troops from Iraq.

Election campaigning was again suspended this time around, after a former municipal legislator, Isaias Carrasco, a Socialist, was shot dead Friday in the northern Basque region.

There have been no claims of responsibility, but police said it bore the hallmark of the Basque separatist group ETA, which has killed over 800 people in its nearly 40-year campaign for an independent homeland.

Spaniards on Saturday received an emotional plea to turn out and vote from Carrasco's daughter, as hundreds attended his funeral.

Pictures of a grief-stricken Sandra Carrasco made the front pages of almost all Spanish newspapers on Sunday, and the conservative press had warned that it could help the Socialists.

"The images ... have provoked a natural feeling of sympathy for the Socialists and Zapatero," the centre-right El Mundo said in an editorial.

The centre-left El Pais commented: "Some are already beginning to put out the idea that a bigger Socialist win than predicted by the opinion polls will be due to the killing of Isaias Carrasco."

After casting his ballot, Rajoy hinted at frustration over the extensive media coverage of the killing.

"My only hope right now is that things happen the way they should, that the only news is that the elections took place, that the winner was the one chosen by all the Spanish people," he said.

During his four years in power, Zapatero has brought in sweeping social reforms, including same-sex marriage, fast-track divorce, laws to promote gender equality and an amnesty for undocumented workers.

Many of the measures have incensed leaders of the Roman Catholic Church but the PP had tried to steer clear of a debate on the reforms, concerned that it would merely mobilize leftist voters.

It has focused instead on rising unemployment and concerns over a sharp rise in immigration.

The elections came as a decade-long economic expansion slows due to the international credit crunch which has hit Spain's key construction sector.

Rajoy, a former education and interior minister, has also accused the government of being soft on terrorism by launching failed peace talks with ETA.

The PP's arguments failed to strike a chord with insurance worker Rosa Cabellero and her 19-year-old son Ruben, who both voted for Zapatero in the immigrant-heavy Madrid suburb of Alcala de Henares.

"The slowing of the economy is widespread across Europe. Immigrants are not a problem here," she said.