Although the ruling right-of-center Popular Party won the most votes, it failed to retain its parliamentary majority and will try to cobble together a coalition or minority government.
But that's unlikely, analysts say, because the party wouldn't get enough seats in the lower house of parliament even by allying itself with the new business-friendly Ciudadanos party that came in fourth place and is seen as the most likely ideological partner.
That sort of combination could lead to a government that would try to roll back highly unpopular austerity measures imposed over the last four years by Prime Minister Mariano Rajoy. He vowed after the vote to try to form a government, but gave no details on how he would do so after winning just 123 seats in the 350-member lower house of parliament.
Also Read
German government spokeswoman Cristiane Wirtz told reporters today that Spaniards deserve congratulations for voter participation of 73.2 percent, up from the 68.9 percent turnout in 2011 that gave Rajoy a 189-seat parliamentary majority.
"But otherwise, I don't yet see so clearly who one can congratulate in this situation," Wirtz said, adding that no one from Germany's government had contacted Spanish officials about the formation of a new government.
If forced from power, Rajoy and the Popular Party would become the third European victims this year of a voter backlash against austerity - following elections in Greece and Portugal seen as ballot box rebellions against unpopular tax hikes and spending cuts invoked during the eurozone's debt crisis.
But Podemos came in a strong third place and Ciudadanos took fourth in their first election fielding national candidates.