Senate Bill 172 by Sen. Pat Steadman, D-Denver, is expected to pass the Democrat-controlled Senate, but its outcome is uncertain in the Republican-controlled House.

Not everyone in the gay community supports the measure. Tom Carllon called civil unions "crumbs" and said if it passes, it is unlikely there would be a push to overturn Lundberg's constitutional amendment outlawing same-sex marriage.

"Civil unions will be an excuse not to upgrade us to marriage," he said.

But Republican Alexander Hornaday, who is gay, urged support of the measure. "This is about family values," he said.