Separatists have made a strong showing in Spanish regional elections, with exit polls showing the Basque National Party winning 27 seats in the Basque parliament.
Spanish Prime Minister Mariano Rajoy was spared political humiliation after his Partido Popular came out top in Sunday's polls in Galicia, his home region.
But a second regional election in the Basque Country has added to Mr Rajoy's problems, with the separatist Euskal Herria Bildu coalition's 21 seats meaning two-thirds of the assembly will be formed of nationalists.
Stringent austerity measures and high unemployment are fuelling discontent across the 17 regions in Spain.
Spain has fallen into its second recession since 2009 and the International Monetary Fund forecasts its economy will shrink 1.3% next year.
Those sentiments are especially raw in the Basque Country, which was holding its first regional vote since armed separatists Eta renounced the use of violence last year.
Mr Rajoy also faces a surge in support for separatism in the wealthy northeastern region of Catalonia, which votes in regional elections on November 25.
Catalan president Artur Mas has promised to hold a referendum on "self-determination" if his Convergencia i Unio coalition is re-elected.
The Spanish government has offered funding to the regions in exchange for more control over local finances. Eight regions, including Catalonia, have so far agreed.
The 17 regions manage their own budgets and are responsible for health and education policies, but their overspending was partly to blame for Spain's failure to hit deficit targets last year.
Mr Rajoy is thought to have been waiting until after the regional elections to decide whether or not to request a sovereign bailout from the euro zone.
The Partido Nacionalista Vasco won 27 of the 75 seats in the Basque parliament, raising the possibility it may ally with Bildu to hold control.
That would mean Basque independence would be at the forefront of political debate, and would represent further conflict for Mr Rajoy.
Bildu has filled the gap left by Batasuna, which was outlawed in 2003, and which many see as linked to the Basque separatist group Eta.
Eta is blamed for 829 deaths during a nearly 50-year armed campaign for an independent Basque homeland.
It announced a "definitive end" to armed activities in October 2011, but has not formally disarmed or disbanded.