Defeated Spanish Prime Minister Jose Maria Aznar has insisted that it was "logical" to blame Eta for the Madrid attacks in the immediate aftermath.
Aznar had expected to lead his party to victory
Voters who rejected his party were thought to be angry that his government rushed to blame the militant Basques.
Some also thought his decision to back the US over the war in Iraq made Spain a target for the bombers.
But in his first public remarks since the election defeat, Mr Aznar insisted that he regretted nothing.
Mr Aznar said he was leaving office with clean hands and with his head held high. He had always acted in Spain's best interests, he said.
"We have spoken the truth at all times and we have shown that," he said.
He said it was "logical" to start by suspecting Eta.
"When it was necessary to open another line of investigation, it was done," he added.
Thirteen people are currently being held over the attacks, most of them Moroccans.
Spanish voters rejected the Popular Party three days after the attacks, even though it had led the opinion polls in the weeks leading up to the election.
Mr Aznar, prime minister for eight years, was already planning to stand down and had hoped to hand power to his chosen successor, Mariano Rajoy.
He refused to speculate on whether the attacks and the election defeat were linked - but he insisted that the election results were entirely legitimate.
The bombings changed the political landscape
"Spain suffered a terrible attack, the most terrible attack Spain has ever suffered and one of the largest attacks there has been in the history of the world," Mr Aznar told Telecinco private television.
"Whoever carried it out had a very clear intention, and the intention was to attack us, to attack Spain, to attack
Spaniards, to destroy our system, our freedoms, our co-existence.
"But look, the results of the elections are absolutely legitimate, and as such they must be respected."
Mr Aznar also condemned the intention by Spain's socialist prime minister-elect, Jose Luis Rodriguez Zapatero, to withdraw Spanish troops from Iraq.
It could be interpreted as giving in to terrorists and would certainly weaken the international coalition against terror, which would be a "very grave error", Mr Aznar said.
"What the terrorists want is for us to throw in the towel," he said.