The poll, conducted by Metroscopia on Dec. 1-2 among 1'000 voters, showed that if an election were held tomorrow the Socialists would win 24.3 percent of the vote, with the opposition Popular Party polling 43.1 percent.
That compares with a 9.1 percentage point advantage for the PP in the last Metroscopia poll a month ago, when the Socialists staged a partial rebound after a cabinet reshuffle.
The latest poll was carried out in one of the toughest weeks for the now deeply unpopular prime minister, Jose Luis Rodriguez Zapatero, whose personal ratings have plunged as Spain has struggled to pull itself out of a deep recession following the financial crisis.
According to Metroscopia, 80 percent of those surveyed had little or no confidence in Zapatero.
The poll coincided with a package of measures to reduce Spain's debt, including the sale of stakes in the national lottery, the partial privatisation of the airports authority AENA and cuts in benefits for the long-term unemployed. Unemployment is around 20 percent, the highest rate in Europe. Based on the poll, the Socialists' share of the vote would be below the 24.4 percent the party polled when Spain held its first democratic elections in 1977, El Pais said. Zapatero was reelected in 2008 with 43.7 percent of the vote.
Of those polled, 91 percent said Spain's economic situation was bad or very bad.