Three Republican senators crossed the aisle Tuesday to help defeat a Pennsylvania resolution that sought to define marriage as a heterosexual union in the state constitution.

The 8-to-6 vote in favor of tabling the measure in the Republican-controlled Senate Judiciary Committee leaves the joint resolution on limited life support.

Senator John H. Eichelberger, Jr. first announced he would sponsor the resolution in May of last year but postponed its introduction until January due to the economy, the conservative lawmaker said.

Eichelberger's resolution would insert the following language into the state constitution: “Only a union of one man and one woman shall be valid and recognized as a marriage in this Commonwealth.”

But three Republican and five Democratic lawmakers disagreed. Joining all the committee's Democrats in killing the resolution were Republicans Pat Browne, Jane Earll and Mary Jo White.

Keystone Progress, a group that opposed the measure, claimed victory after the vote.

“We should celebrate, but we need to remain vigilant,” Michael Morrill said on the group's blog. “It is unlikely, but it is possible that the bill could come to life again.”

The group said its members responded to a call to action with over 120,000 emails and thousands more calls and letters urging committee members to reject the measure.

Pennsylvania voters – like much of the country – are clearly divided on the issue. According to a June, 2009 Franklin & Marshall statewide poll, 48% of respondents support defining marriage as a heterosexual union in the state constitution, while 46% said they were opposed. However, a majority of voters (58%) support civil unions for gay and lesbian couples.

Currently, Pennsylvania bans gay marriage by law, which anti-gay marriage foes say leaves the law vulnerable to being overturned by a judge.