Spain's outgoing interior minister Alfredo Perez Rubalcaba launched his election campaign to become prime minister after being formally declared on Saturday the governing Socialist party's candidate in next year's vote The 59-year-old Alfredo Perez Rubalcaba resigned Friday as interior minister and deputy premier in Prime Minister Jose Luis Rodriguez Zapatero's government to focus on the campaign. His resignation is likely to take formal effect early next week. The Socialists officially chose Rubalcaba as their candidate at a meeting early Saturday and followed the announcement with a large campaign rally at Madrid's main conference center. Zapatero decided in April, a month before regional and municipal elections, not to seek a third term in office. The May elections gave the center-right opposition Popular Party a 10 percentage-point lead over the Socialists and most observers say the gap is too big to overcome. "Let's make it happen," Rubalcaba said as he rallied his party. General elections must be held by March 2012. Spain's economy is struggling to overcome recession and is saddled with a 21.3 percent unemployment rate — the highest in the eurozone. Although Zapatero said he intended to finish his legislature — and has enough parliamentary support to do so — there is speculation he may opt to hold the election early. Rubalcaba acknowledged that Spain was going through difficult times and said this was because the economy had lost an important sector when the real estate bubble burst. Rubalcaba is known to be a workaholic and is well respected in parliament for his consummate speaking skills and as a veteran of Socialist governments that ruled Spain for nearly 14 years starting in the early 1980s. Zapatero was elected in 2004 after two terms of Popular Party rule, and Rubalcaba joined him in the Cabinet. Rubalcaba reminded party members how far Spain had come since democracy was re-established after Gen. Francisco Franco's 1936-1975 dictatorship. "I entered politics like many of you, to fight for freedom and liberty," he told the party gathering.