The ruling Convergence and Union alliance, or CiU, is expected to get the most votes in regional elections in Spain's Catalonia on Sunday, according to an exit poll by TV3, Catalan public television.
CiU, whose leader Artur Mas says he will call a referendum on Catalan independence from Spain, is seen winning 54-57 seats in the 135-seat regional assembly, or parliament.
That is down from the 62 seats it currently holds, and far from the absolute majority Mr Mas had aimed for.
The Republican Left, or ERC, would take second place, the exit poll showed.
The ERC is also a separatist party and could ally with Mr Mas to push for a referendum.
Frustration over high unemployment and a deep recession have fuelled a separatist resurgence in Catalonia, where polls show that for the first time more than half of the people want to break away from Spain.
Many Catalans believe their economy would be more prosperous on its own, complaining that a high portion of their taxes go to the central government in Madrid.
Mr Mas, who adopted the independence cause in September after a massive street demonstration, campaigned on a promise to hold a referendum on secession.
If he carries through with the pledge, it will put him on a collision course with Madrid, where Prime Minister Mariano Rajoy will use the constitution to block a referendum.
"Catalonia has never faced elections this important," Mr Mas said at a campaign rally this week. He told supporters he wanted to be the last president of Catalonia within Spain.
A strong mandate for Mr Mas and other Catalan independence leaders from the left will undermine Mr Rajoy's mission to persuade investors of Spain's fiscal and political stability.
Spain's deep recession and high public deficit have put it at the heart of the eurozone debt crisis and the government's borrowing costs are painfully high.
Alicia Sanchez-Camacho, the candidate for Mr Rajoy's People's Party in Catalonia, has campaigned on a message that leaving Spain and the European Union would lead to economic disaster.
The PP is vying to be the second biggest party in the Catalan parliament, with opinion polls forecasting it will win 17 seats.