Jose Socrates was sworn in as Portugal's prime minister on Saturday vowing to keep friendly ties with the United States. Underscoring his commitment to a stronger European Union, the Socialist leader also said he would seek to hold a referendum on the EU constitution in December this year. Touching on relations with Washington, Socrates said Portugal's European links coexisted with its "calling as a Atlantic nation". The government "will assure the active and committed presence of Portugal in NATO and the continuation and deepening of our reciprocal relations of friendship and cooperation with the United States of America", he said in an address after being sworn in. Socrates spoke with Bush on March 4 shortly after naming his cabinet and assured him of Portugal's cooperation with Washington, weekly newspaper Expresso reported on Saturday. Socrates, a 47-year-old former environment minister, said the party's clear win meant his government was empowered to carry out its programme to jump-start the sagging economy through technological training and investment. The Socialists won 121 of the 230 seats in parliament. The government is Portugal's fourth in three years. Socrates said he would seek to hold a referendum on the EU constitution in December 2005 jointly with municipal elections. The constitution would have to be changed to allow the joint voting.