A new communist party in the Basque region has made large gains in yesterday's elections.
The Communist Party of the Basque Lands came in a surprisingly strong fourth place after it was given the backing of Batasuna, a party banned as the political wing of armed separatists ETA.
The ruling nationalist party won the election, but in a blow to their hopes for their plan on autonomy, they failed to win an absolute majority.
Basque Premier Juan Jose Ibarretxe emerged weakened in yesterday's vote for the regional parliament as radical separatists put in a stunning performance that could give them sway over the next government.
Mr Ibarretxe and his moderate Basque Nationalist Party had been seeking endorsement of their plan for near independence from Spain but instead lost four of their 33 seats in the 75-member legislature, threatening the party's 25-year grip on power.
That development was decried by the right-of-centre Popular Party as giving ETA, classed as a terrorist group by Spain and the European Union, representation in parliament.
"ETA for the first time was not going to be in the Basque parliament and now it has increased its number of members from seven to nine and, what's more, has become the arbiter of the situation," former Interior minister Angel Acebes said.
He blamed Socialist Prime Minister Jose Luis Rodriguez Zapatero for not trying to ban the communists after they won the endorsement of Batasuna.
Results showed the restive region still about evenly split between Basque nationalists seeking greater autonomy from Madrid and Spaniards who support territorial unity.
But the pro-Spanish parties picked up one potentially crucial seat from the nationalists.
Mr Ibarretxe could muster a minority government with 33 seats and no immediate prospects for an absolute majority of 38 unless the communists came to his aid.
"We have won the elections," Mr Ibarretxe told cheering supporters, denying the result was "bittersweet". "The game has gotten a little complicated but we are going to win," he said.