Zapatero has called elections for November 20, four months earlier than originally planned, in the hope that faint signs of an economic recovery could offset unpopularity after years of deep austerity measures in a country where one in five is unemployed.

However, since August, the worsening euro zone crisis has forced the government to push through even more reforms as it tries to avoid a bailout like in Greece, Portugal and Ireland.

"We'll continue to adopt measures if necessary," Zapatero told reporters after a cabinet meeting, given continued uncertainty in Greece, which remains in talks to avoid default.

Even though the Spanish parliament is officially dissolved, a permanent legislative committee can approve emergency measures in the event the euro zone crisis takes a turn for the worse.

The Gesop opinion poll for Catalonian daily El Periodico showed on Monday a total of 46 percent of voters intend to choose the PP. It also showed the Socialists, led into the elections by former Interior Minister Alfredo Perez Rubalcaba, obtaining 31.4 percent of votes.

The election campaign will officially start on November 4.