The conservative People's Party (PP) of acting Prime Minister Mariano Rajoy has won most seats in Spain's parliamentary election but is short of a majority.
Spain's other main party, the Socialist PSOE, is in second place.
The left-wing Unidos Podemos alliance and centre-right Ciudadanos are third and fourth.
The vote has failed to break six months of political deadlock since December's inconclusive poll. But Mr Rajoy said he had a right to resume office.
Mr Rajoy said he hoped political parties would reach a deal within a month.
"It would be nonsense to lose time for several more months," he said.
Official results give the PP 137 seats in the 350-seat parliament, up 15 from the 122 they won the December ballot.
The PP now faces a similar challenge to form a government as after the December poll. It needs support from a number of other parties in order to achieve a voting majority.
One figure from the second-place Socialist party has backed Mr Rajoy, saying he should be in government "as soon as possible". Guillermo Fernandez Vara, leader of the Extremadura region, said: "That's what voters have told us and that's what we have to do."
But the party's secretary, Cesar Luena, said the party would not support Mr Rajoy.
"The PSOE wants to replace Rajoy," he said.
Analysis: Sarah Rainsford, BBC News, Madrid
The prospects of resolving the political stalemate do not look good.
It was the failure of previous attempts to agree a coalition that sparked a re-run of the ballot in the first place, and Sunday's election resulted in no major changes.
The PP won the election and even increased its support - but not by enough to govern alone.
So once the celebrations stop, the wrangling over coalitions will begin and it will not be easy.
The other surprise from Sunday's vote was that the left wing protest party Podemos did not soar in the polls. It is possible that voters were turned off more radical parties, after the UK voted for to leave the European Union - and shook Spain's fragile economy.
Spain has endured six months of political paralysis. All parties are now under pressure to reach a compromise, form a coalition, and get back to the business of governing.
The PSOE won 85 seats, confounding an earlier exit poll suggesting it would slip into third place, but still five fewer than in December.
All the other parties lost votes or seats, or both. Unidos Podemos and Ciudadanos, both relative newcomers, won 71 and 32 seat respectively.
Unidos Podemos was the worst-affected, losing more than a million votes and failing to meet expectations that it would become the country's main left-wing party.
The Spanish election came days after the UK voted in a referendum to leave the EU.
Mr Rajoy had sought to portray the election as a choice between economic stability and the uncertainty offered by Unidos Podemos ("Together We Can"), a coalition led by anti-austerity party Podemos that emerged just two years ago in protest against austerity measures demanded by Brussels.
Podemos leader Pablo Iglesias has denied his party is Eurosceptic, telling the BBC he was "sad" at the outcome of Britain's referendum.
"We hope for a different Europe, we will fight for a Europe with social rights as a reality and we are for Europe and the people in Europe."
December's election was a watershed for Spain, because the PP and the PSOE had previously alternated in power since the restoration of democracy in the 1970s.
But after months of talks no party was able to form a coalition or minority government.
Unidos Podemos and other left-wing groups argued that the PP, under Mr Rajoy, had been discredited because of austerity and the chronic unemployment that has plagued Spain since the 2008 financial crisis.
The PP, however, says Spain's improved economic performance is proof that its policies have worked.
Casting his vote on Sunday, Mr Rajoy urged Spaniards who "love and feel for their country" to make their voices heard.
"Spain will be what the Spanish people want it to be, it will have the government and the members of parliament the people want," he said.