It's a benefit to same-sex couples, and Ferrandino expects a fight, but he said others would benefit as well.

"It's going to be controversial, but if you think about it, it shouldn't be," Ferrandino said. "It's something that's smart government policy to try to encourage people to plan ahead."

The bill would also allow an unmarried partner to sue for wrongful death or collect workman's compensation should the other partner be killed on the job. It would cement the right for unmarried partners to visit each other in the hospital as well.

In 2006, socially conservative lawmakers like Sen. Shawn Mitchell, R-Broomfield, proposed similar legislation allowing so-called "designated beneficiary agreements."