Spain's King Felipe dissolved the parliament on Tuesday and announced a repeat national election for June 26, after inconclusive elections in December.
Spain’s acting Prime Minister Mariano Rajoy turned down a chance to form new government after the elections, in which his People's Party emerged victorious but lost its majority.
The re-run is not expected to herald a major shift in voting patterns, opinion polls show, likely forcing bickering leaders to once again try to forge a coalition.
"Let's hope we've all learned our lesson and that the next parliament reaches an agreement (on forming a government) as soon as possible," speaker Patxi Lopez told a news conference, confirming the king had signed the election decree.
Conducted against a backdrop of economic hardship and with a political elite tainted by accusations of corruption, December's election marked the end of the dominance of the two traditional parties, the PP and the Socialists, that have governed Spain since its transition back to democracy in the mid-1970s.
Their power base was eroded by the emergence of two newcomers, anti-austerity Podemos (We Can) and centrist Ciudadanos (Citizens).
During negotiations the quartet of party leaders failed to bridge significant policy gaps, including how to manage the economy and how to soothe an independence drive in regional powerhouse Catalonia.
A blame game between parties on who was responsible for the repeat election is likely to dominate campaigns - due to kick off formally on June 10 - as politicians seek to galvanise frustrated voters and ward off a rise in abstention.
Some of the parties are already considering alliances.
Podemos may team up with the former communists of Izquierda Unida (United Left), which would help unite the vote on the left. That may pose a strong challenge to the Socialists, which came second in the December vote.
In the last election, Podemos finished third and Ciudadanos fourth.
The political uncertainty has yet to derail Spain's continued recovery from a deep recession, with growth expanding at a steady rate in the first quarter and output due to increase at one of the fastest rates in the euro zone this year.
But Spain is under pressure to trim its public deficit after overshooting its goal by a wide margin last year, meaning it can ill-afford any slowdown in the months to come.
The European Commission said on Tuesday that Spain's deficit could come in at 3.9 percent of gross domestic product in 2016 - the highest in the euro zone and above the 3.6 percent envisaged by the acting government - and warned that it would not drop below a required threshold of 3 percent in 2017 as planned.