( AFP ) - Spain votes in a general election on Sunday, two days after the Socialist government's record in battling ETA was thrust into the spotlight when a gunman believed to belong to the Basque separatist group shot dead a former city councilman.
All political parties called off campaigning on Friday just hours before it was officially due to close at midnight after Isaias Carrasco, a Socialist, was shot several times at close range in the Basque town of Mondragon.
He died shortly after in hospital.
There has been no claims of responsibility for the attack but the government swiftly blamed ETA, which has killed over 800 people in bombings and shootings in its nearly 40-year campaign for an independent Basque homeland.
Zapatero, tipped to win a second mandate in Sunday's vote, accused ETA of seeking to upset the electoral process and appealed for national unity.
"Together we will put an end to this scourge which has been attacking Spanish society for decades," he said in a televised address.
Carrasco's assassination would be the first death by ETA in Spain since it officially called off a 15-month ceasefire on June last year, citing a lack of concessions by the government in its tentative peace process with the outfit.
ETA in December 2007 claimed responsibility for the deadly shooting earlier that month of two Spanish police officers in southern France.
Monday was the last day that opinion polls of voting intentions could be published and surveys released that day gave the Socialists a lead of about four percentage points over the conservative opposition Popular Party (PP).
Zapatero came to power in a surprise election win on March 14, 2004 amid the shock of train bombings in Madrid by Islamic extremists that killed 191 people just three days earlier.
Voters were infuriated over the PP's insistence that Basque separatist group ETA was to blame for the attacks even though evidence pointed to Islamic extremists angered by Madrid's role in the Iraq war.
Analysts do not think the assassination will significantly influence the outcome of Sunday's election.
The president of the Sigma Dos polling firm, Carlos Malo de Molina, said the assassination would have conflicting effects at the ballot box but would not be a decisive factor.
The attack could fuel "frustration" at the unending violence on the part of ETA and the absence of a solution to the "Basque problem" but "on the other hand the victim is Socialist, and people will back the victim," he told AFP.
Throughout Zapatero's first term in office, the PP has railed against the government's attempt to negotiate with ETA although its campaign had focused on immigration and the slowing economy.
Spain's parliament convened a special session late on Friday afternoon where a joint statement in condemnation of the assassination issued by all political parties with a seat in the assembly was read out.
But at a news conference held shortly after, PP lawmaker Ignacio Astarloa deplored the fact that the statement did not mention that there would be no more talks with ETA.
Rajoy, whom Zapatero defeated in 2004, underscored his party's opposition to negotiating with ETA, in the address he made to condemn the attack.
"Everyone knows what I think. Only the terrorists are to blame. The only option is to defeat them with the law. They should lose all hope of achieving their political objectives," he said.
Spanish authorities have adopted a hard line against ETA since it called off its ceasefire, detaining dozens of suspected members of the outfit and its banned political wing Batasuna.