Socialist Party leader José Sócrates, who vowed to legalize same-sex marriage if reelected as prime minister of Portugal, won the election held on Sunday and is set for another four years in office, reports Reuters.

While promising social reforms, Sócrates was reelected without a parliamentary majority, which will make passing liberal legislation an uphill challenge. The Socialist Party won 36.6% of the vote and gained 96 of the 230 seats in parliament. Meanwhile, the Social Democrats, the biggest opposition party to Sócrates’s reforms, obtained 29.1% of the vote and 78 seats.

If he plans to follow through on his campaign promise, Sócrates must also face the influential Roman Catholic Church. In 2007 his government clashed with the Vatican over the issue of abortion, but eventually Sócrates got the procedure legalized in the overwhelmingly Catholic state.

Despite the challenges, Sócrates said he will not "waver in implementing reforms, even when they are met with incomprehension, obstacles, and opponents," according to the Associated Press.