Voters in Catalonia have overwhelmingly backed parties that favour breaking away from Spain, but the region's biggest party saw its majority in parliament fall.
Artur Mas, the current Catalonia president and leader of the centre-right Covergence and Union (CiU) alliance, had promised a referendum on "self-determination" if the election had given him a strong mandate.
However, with just 50 seats in the 135-seat regional parliament the CiU was 18 short of the absolute majority he desired.
Mr Mas, who during campaigning said he hoped to be the last president of Catalonia reliant on Madrid, acknowledged that he would now have to share power as he fights for greater sovereignty for the economically powerful Spanish region.
"From this result we note that we are clearly the only force that can lead this government, but we cannot lead it alone. We need shared responsibility," Mr Mas told supporters in Barcelona.
"There must be a period of reflection in Catalonia over the coming days. The presidency must be taken up, but we will also have to reflect along with other (political) forces," he said, without naming a particular party.
The pro-independence leftist party ERC was second with 21 seats after 97% of the ballots had been counted.
"The vote is fragmented but the message is clear," Ferran Requejo, political science professor at Barcelona's Pompeu Fabra University, said.
"Two-thirds of the electorate voted for parties that are in favour of calling an independence referendum, but Mas has been hit hard for his austerity policies."
Like the Basque Country, Catalonia - a northeastern region of 7.5 million people - has its own language and sees itself as different from the rest of Spain.
Until recently, Catalans were content with just pushing for greater autonomy, and stopped short of seeking independence.
But Spain's economic woes, including a 25% unemployment rate, and tough austerity measures imposed by Madrid have added to the Catalans' discontent and persuaded many they would be better off on their own.
Catalonia has a significant weight in Spain's economy, accounting for one-fifth of its total output, and a greater share of its exports.
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