Story highlights The 10-8 vote is on strict party lines, with Democrats in favor and Republicans opposed

The repeal has no chance of winning approval from the Republican-led House

Democrats say repeal would mean federal benefits for legally married same-sex couples

Republicans argue it will be costly and alter the institution of marriage

Democrats on the Senate Judiciary Committee voted Thursday to repeal the federal law that defines marriage as between one man and one woman.

The vote that sends the proposal to the full Senate floor was considered symbolic because the measure has no chance of getting passed by the Republican-led House.

All eight Republicans on the Judiciary Committee voted "no" Thursday, while all the 10 majority Democrats supported the measure that would provide equal federal benefits to legally married same-sex couples.

Democrats and gay rights advocates hailed the vote as historic in the continuing effort to legalize same-sex marriage and end separate treatment for legally married same-sex couples.

Committee Chairman Pat Leahy, D-Vermont, called it "an historic step forward in righting an injustice that goes right to the core of what we stand for in this country -- freedom and equality."

However, social conservatives said the repeal measure disrespected the beliefs and wishes of mainstream America.

"Marriage is not some prize that liberals can award to a small, vocal and already well-off special interest group," said a statement by Tony Perkins, president of the Family Research Council. "Marriage between one man and one woman was created prior to the formation of any governments and is given benefits by governments because it uniquely contributes to a productive society."

Under the Defense of Marriage Act, passed in 1996, only legally married couples as defined by the law are entitled to more than 1,000 federal marriage benefits such as continued Social Security payments to spouses after death.

Repealing the measure means that same-sex couples wed in the six states and the District of Columbia, which have legalized gay and lesbian marriages, would be eligible for full federal benefits afforded other couples, regardless of where they live, said Sen. Dianne Feinstein, D-California, who sponsored the proposal.

Feinstein and other Democrats said the repeal would not require states to legalize same-sex marriage or otherwise impede on a state's rights on the matter.

Republicans said the repeal would alter the institution of marriage between a man and woman, and also would increase the cost burden on the federal government by expanding the number of eligible beneficiaries.

"No one has paid into Social Security expecting benefits to be paid to same-sex partners," said Sen. John Cornyn, R-Texas.

Leahy responded that people who have paid into Social Security like anyone else should be able to receive benefits, whether or not they have legally married someone of the same sex.

He and other Democrats said the issue was about equal treatment under the law.

However, Republican Sen. Orrin Hatch of Utah complained of a broader impact, saying "it is no secret that advocates want to use the courts to force states to legalize and recognize same-sex marriage."

To Democratic Sen. Al Franken of Minnesota, the repeal would be one step in the right direction.

"When we do pass it, straight people aren't suddenly going to become gay," he said, adding: "We'll do just fine, really."