An obscure Communist party could hold the balance of power in the Basque parliament following Sunday's election thanks to Spain's drive to ban radical pro-independence party Batasuna from the ballot.
The Communist Party of the Basque Lands (EHAK), running in an election for the first time, was until recently virtually unknown and never expected to win a seat.
But because Batasuna, banned as the political wing of armed separatists ETA, threw its support behind EHAK, the political novices are now expected to grab half a dozen or so seats in the 75-member Basque parliament.
Polls show premier Juan Jose Ibarretxe, a moderate Basque nationalist, is favoured to win re-election but with a minority coalition and a tenuous hold on power. So EHAK could play kingmaker in the regional parliament.
That could bring more friction with the Madrid government, already at odds with Mr Ibarretxe over his plan for "free association" with Spain.
"The truth is we never expected this," said Maite Aranburu, 28, who heads the party ticket in the province surrounding Bilbao. "We were just testing the waters."
Batasuna won 10 per cent of the vote and seven seats in the 2001 Basque election.
Spanish courts and parliament allege Batasuna forms part of ETA, Western Europe's most active guerrilla group and responsible for more than 800 killings since 1968. Batasuna denies the charges it used its political clout and public funds to support the violence.
Spain's governing Socialists, who backed the banning of Batasuna and helped prevent a replacement party from getting on the ballot, say they are helpless under the law to stop EHAK, provoking outrage from the conservative opposition Popular Party.