A Colorado House panel on Thursday killed a bill that would give gay and lesbian couples many of the benefits and responsibilities of marriage.

After hearing six hours of testimony, the Republican-controlled Judiciary Committee voted against sending the measure to a second committee. As expected, the vote split along party lines.

The measure, which was sponsored by two openly gay Democrats, Representative Mark Ferrandino and Senator Pat Steadman, both from Denver, won passage in the Senate last Thursday with the help of three Republicans.

While all six GOP committee members were on record as opposing the measure, supporters had hoped the votes of their colleagues in the Senate would affect the outcome in the committee.

“This is not a radical concept,” Ferrandino told the Denver Post. “It's a mainstream concept. … This does not end marriage.”

While careful not to mention names, Ferrandino had claimed that there was Republican support for the measure in the GOP-controlled House.

It is the second high-profile loss for gay rights activists in a month. Three weeks ago, the Maryland House decided to shelve a gay marriage bill.

Delaware, however, continues on track to passing a similar civil unions bill.