By Steve Kingstone BBC News, Madrid

There can only ever be one winner, but both of Spain's main parties are looking at these results and legitimately claiming success.

Socialist Party supporters can claim victory, fair and square

For Jose Luis Rodriguez Zapatero, a hard-fought victory finally lays to rest the accusation that he is an "accidental prime minister" who only came to power courtesy of the devastating and destabilising Madrid train bombings of 11 March 2004.

This time he won fairly and squarely, on his record, as the Socialist Party (PSOE) enjoyed its best showing in more than two decades.

For its part, the conservative opposition Popular Party (PP) can claim to have enjoyed the biggest increase in vote-share.

Whereas PSOE won an extra 1% of the popular vote compared with 2004, the PP's share jumped by 2.4%. This was by no means a crushing defeat.

Seeking alliance

Between them, the big two squeezed Spain's smaller parties - notably the United Left, whose leader hastily resigned; and the Republican Left of Catalonia, which has shared a fractious on-off coalition with PSOE in Spain's wealthiest region.

Sunday's turnout nearly matched the level of Spain's 2004 elections

The Socialists also won the popular vote in the Basque country for the first time since 1993, at the expense of the Basque Nationalist Party, whose hopes for a referendum on independence may now have to be revised.

Just seven seats short of an absolute majority in Congress, Mr Zapatero will look to these and other regional parties as he builds a parliamentary alliance.

Sunday's turnout was high: at 75.3%, only slightly down on 2004.

In part, that may be a consequence of the murder last Friday of the former socialist councillor, Isaias Carrasco, which the government blamed on the Basque separatist group Eta.

Coming 48 hours before the vote, it was a sombre reminder to Spaniards of their democratic duty.

The elevated turnout may - as some have argued - have benefited PSOE, but the result was consistent with weeks of opinion polls, and it would be wrong to suggest that Friday's attack swung the election.

Benefit of doubt

On balance, a majority of voters just about agreed that their country was moving in the right direction. With unemployment and inflation uncomfortably high, there may not be a feel-good factor in Spain, but nor is there necessarily a "feel-bad" factor at this stage.

Pursuing more reforms may provoke Mr Zapatero's opponents

The electorate did not quite buy the apocalyptic economic scenario set out by the PP leader, Mariano Rajoy, who warned that rising immigration would become a problem during a downturn.

Instead, they have given Mr Zapatero the benefit of the doubt when he says Spain's current troubles merely reflect a wider global slowdown.

In victory, the prime minister promised "a new phase without tension, and which excludes confrontation - an era based on agreement".

His hope is that this second-term triumph will draw a line under the lengthy and bitter debate about 11 March 2004. And even if it does not, managing parliamentary business should come easier to PSOE in this legislature with an additional five seats.

The future mood will depend on how Mr Zapatero chooses to spend his limited credit from voters.

During his first-term, the legalisation of gay marriage and fast-track divorce provoked the ire of the Catholic Church, as well as the PP.

Should he choose to continue down a liberal path - for instance, by seeking to relax abortion laws - he will face a fierce fight.

PSOE's performance on homeland security will also come under the microscope, following a failed policy of dialogue with Eta last time around.

Rajoy undermined

In the short term, Mr Rajoy will probably hang on as PP leader, but it is unlikely that he will be given the chance to become a three-time election loser.

Mariano Rajoy may not be allowed to fight a third election

The 52-year-old Galician has vast experience as a government minister, but has never entirely cut it as party leader.

Over two televised debates, Mr Rajoy lost narrowly on points to Mr Zapatero, when he really needed to score a knockout. And his genuine best efforts to lead the PP have been undermined for months by senior party colleagues jockeying for position in the likely succession race.

On one thing, all the main parties are agreed - in the wake of Friday's political killing, this election showed Spanish democracy to be secure and healthy.

In contrast to the rancour and recriminations of four years ago, it was a united and mature attitude.

Now let's see how long it lasts.