Socialist Jose Luis Rodriguez Zapatero took the oath of office in front of King Juan Carlos Saturday, beginning his second term as prime minister with a flagging economy and Basque separatism as his chief concerns.
After the brief ceremony at the royal Zarazuela Palace, Zapatero, who was re-elected on March 9, is to announce his government.
Key members of the outgoing cabinet, such as Foreign Minister Miguel Angel Moratinos, Economy Minister Pedro Solbes, Interior Minister Alfredo Perez Rubalcaba and Deputy Prime Minister Maria Teresa Fernandez de la Vega, are expected to remain in their posts.
The only surprise could be the naming of outgoing housing minister Carme Chacon as the country's first woman defence minister, Spanish media said Saturday.
Chacon, 37, considered a rising star in the Socialist Party, would succeed Jose Antonio Alonso, who last month was named speaker of the lower house of parliament.
Spanish lawmakers on Friday confirmed Zapatero as prime minister for a second term.
He received the backing of all 169 Socialist deputies, while 158 legislators voted against him and 23 abstained.
The vote came two days after he failed to receive the necessary absolute majority in a first round ballot. But this time, only a simple majority -- more votes than any other candidate, of whom there were none -- was needed.
The Socialists were seven seats short of an absolute majority in the 350-member lower house of parliament.
In a brief address prior to the vote, Zapatero again identified the sluggish economy, the fight against the armed Basque separatist group ETA and a continuation of his liberal social policies as the priorities of his second term.
He called for a country that was "progressive, integrated, prosperous, strong, efficient, diverse" and also "politically and socially united against the threat of terrorist violence."
Zapatero also reiterated his appeal for a cross-party strategy to combat ETA, which has killed 822 people in its nearly 40-year campaign for an independent Basque nation encompassing parts of northern Spain and southwestern France.
Zapatero's first four-year term was marked by confrontation with the conservative opposition Popular Party over his failed attempt to negotiate peace with ETA.
Turning to another key area, the Spanish leader urged "far-reaching and immediate measures, and long-term reforms" to boost the economy, where the global credit crunch and rising interest rates have hit Spain's once-buoyant construction industry.
The Bank of Spain predicts the economy will grow by 2.4 percent this year, its lowest rate in over a decade, after expanding 3.8 percent in 2007.
The prime minister acknowledged he did not have a clear majority in parliament, but that "many scenarios are possible" in order to achieve the necessary support to pass legislation.