BUCHAREST (Reuters) - Romania’s ruling Social Democrats hope to organize this autumn a referendum to restrict the constitutional definition of family, which would effectively rule out the possibility of legalizing same-sex marriage, party leader Liviu Dragnea said on Saturday.

FILE PHOTO - Social Democratic Party (PSD) leader Liviu Dragnea exits the parliament's main hall, in Bucharest, Romania June 18, 2017. Inquam Photos/Octav Ganea/via REUTERS

The plan for a referendum came about after the Coalition for the Family, a civil society group, collected 3 million signatures last year in favor of changing the constitutional definition of marriage as a union strictly between a man and a woman from the existing “spouses.”

Under Romanian law, the constitution can be changed after a proposal by the president, the government, a quarter of all lawmakers or at least 500,000 citizens. Parliament must approve any revision, which must then pass a nationwide referendum.

“It is known that we are committed ... in this direction,” state news agency Agerpres quoted Dragnea as saying at a party meeting at a resort on the Black Sea.

“Our intention is to end up organizing the referendum to change the constitution on the family issue this autumn.”

Few politicians openly support same sex marriage or even civil partnerships in the socially conservative eastern European nation of 20 million, where the Orthodox Church yields significant influence.

Notable exceptions include centrist President Klaus Iohannis, an ethnic German, who has said that as a member of an ethnic and religious minority, he supports tolerance and openness towards others who are different while rejecting religious fanaticism and ultimatums.

The opposition Save Romania Union (USR) also held an internal vote on the issue and decided to oppose the referendum.

In June, dozens of Romanian rights groups jointly asked parliament to reject the proposed constitutional change that they said would push the European Union state onto a populist, authoritarian track leading to an erosion of democratic rights and liberties.

The Coalition for the Family also supports cancelling subsidies for contraception and elective abortion, forcing parents of minors to have counseling if they want to divorce, and lowering some taxes for married couples.

Restricting the definition of family based on a marriage between man and woman also would hurt single parents, non-married couples and other non-traditional parenting units, rights groups have said.