Mariano Rajoy is modern Spain's sixth prime minister

Mariano Rajoy, the leader of the conservative Popular Party (PP) which won a landslide majority in Spain's November 20 general elections, has become the country's sixth prime minister since the return to democracy in the mid-1970s.

The replacement of Socialist José Luis Rodríguez Zapatero by Rajoy was formalized at a ceremony at the royal La Zarzuela palace this morning, when the 56-year-old swore the oath of office before a Bible, the Constitution and a crucifix as the king looked on. Also among those present were Elvira Fernández and the outgoing premier Zapatero. After the ceremony Rajoy had a lengthy private conversation with King Juan Carlos.

The new prime minister is expected to release the names of his Cabinet ministers this evening

On Tuesday Rajoy had been voted in as prime minister in Congress, where members of the PP were joined by the Foro Asturias and the Navarre People's Union (UPN) in casting 187 votes in favor, while 149 votes against were lodged by the Socialist Party; the Catalan CiU nationalist bloc; the United Left; Union, Progress and Democracy (UPyD); the Galician Nationalist Bloc; Geroa Bai and Compromís-Equo.

The biggest surprise of Tuesday congressional session was the abstention of Basque abertzale left coalition Amaiur, which aligned itself with the Basque Nationalist Party (PNV) and the Canaries Coalition (CC).

"Given the voting system, we abstained because we will not participate in the election of a prime minister in the Spanish government," Amaiur said in a statement on Twitter.

"I am content, because there have been many years of hard work," were the new prime minister's first words on the floor of Congress. "I am full of enthusiasm, excitement and determination to take Spain forward."

Just hours after his investiture vote, German Chancellor Angela Merkel called on Rajoy to implement "as soon as possible and with commitment" the reforms he announced Monday, which include raising pensions and trimming the deficit by 16.5 billion euros. The incoming prime minister hasn't specifically said where he will make the cuts.

The incoming government will have a full plate to deal with: Amaiur, the latest incarnation of the abertzale left, which has been absent from parliament for 18 years, ensured that the question of ETA and the Basque Country was to the fore during the investiture.