LISBON - Portugal's main opposition party, the Social Democratic Party (PSD), on Saturday elected Rui Rio as their new leader.

The 60-year-old former mayor of the northern port city of Porto won 54 percent of the votes in a two-way race, defeating Pedro Santana Lopes, a former mayor of Lisbon.

Turnout was 60 percent, with 42,254 voting out of 70,385 eligible members.

In his victory speech, Rio promised that the PSD under his leadership would provide "firm and watchful opposition" but would "not be demagogic or populist."

Rio is expected to breathe new life into a party that is on the decline but still has the most seats in Portugal's parliament.

Despite being a major party in the country, the PSD suffered heavy losses in local elections in October.

On the stump, Rio promised to collaborate with the ruling Socialist Party to ensure reforms in Portugal.

Rio will officially take over at the PSD party conference beginning on Feb 16.