Power to Basque nationalists and anger at economic suffering pose a challenge for Spain's Prime Minister Mariano Rajoy on Sunday when two key regions vote for new leaders.
The vote in the Basque Country, the first since armed separatist group ETA declared an end to its bombings and shootings, is marked by a surge in support for a coalition that is continuing the push for independence democratically.
Meanwhile an election in Galicia, Rajoy's home region and political stronghold, will gauge how deep anger at the recession and his economic management has spread.
Rajoy is already grappling with rising separatism in Catalonia, which he says is a threat to Spain's unity as he fends off warnings that the country will need to be bailed out by its neighbours.
"The biggest mistake we could make is to add a political and institutional crisis to an economic crisis," he said recently, referring to Catalonia and to the Basque Country, called Euskadi in the Basque language.
Polls show a new coalition of left-wing Basque separatists, Euskal Herria Bildu, will finish second, behind the conservative Basque Nationalist Party (PNV), forcing the latter to make an alliance.
"If it is with Bildu, the question of (Basque) identity, of ties with Spain, will play a central role in its coalition," said Anton Losada, political science professor at the University of Santiago de Compostela.
Bildu was created last year to fill the space left by the Batasuna party which was outlawed in 2003 for alleged ties to ETA and includes independent candidates who are former Batasuna members.
ETA is blamed for 829 deaths during its four-decade armed campaign for an independent Basque homeland in parts of southern France and in the northern Spanish region.
The Spanish Basque Country is home to 2.2 million people and includes the major city of Bilbao. Its current unemployment rate, though high at 14.5 percent, is well below the national average.
On October 20, 2011, ETA announced a "definitive end" to its armed activities, but has not formally disarmed or disbanded as the Spanish government demands.
In Rajoy's native region of Galicia, polls indicate his conservative Popular Party faces a tight race to defend its narrow absolute majority, ahead of Spain's other main party, the Socialists.
Rajoy's party could see its share of the vote drop if voters use the ballot as a protest against the steep spending cuts and tax increases he has passed to slash Spain's public deficit since he came to power in December.
Sunday's polls there will offer "a complete analysis of the two parties who have alternated in power in Spain for the past 30 years," wrote editorialist Laureano Lopez in an editorial in regional newspaper La Voz de Galicia.
Rajoy has insisted Spain must stay united as it fights to stabilise its public finances and pushes through reforms that he says will strengthen its economy in the long term, in the face of mass street protests.
Campaigning in Galicia on Friday, he said that voting PP "is to bet on the values that unite all Spaniards -- values that are the same for us in Galicia, in the Basque Country, Catalonia and all of Spain."
In Sunday's vote, he added, "there is a choice between stability, moderation and common sense, or confusion, uncertainty and constant stress."
Unemployment in Galicia, population 2.8 million, has surged to 21 percent, close to the national average of nearly 25 percent, since its Popular Party president Alberto Nunez Feijoo took power in 2009 at the height of the financial crisis.
"We will see how far and how strongly the wave of discontent generated by the crisis moves -- if it moves at all," Lopez wrote.
Polls open at 9:00 am (0700 GMT) and close at 8:00 pm (1800 GMT).