But the complete absence of Republicans, currently in control of state government, at Thursday's press conference indicated how unlikely the bill’s passage is in the near future.

There's little hope that Gov. Scott Walker will change his mind on the issue. Although he has tried to avoid discussing the divisive social issue, he said at one point last year that he believed the state's gay rights laws, including the marriage ban, amounted to a "healthy balance." Earlier this month Walker said he hasn't seen a "significant movement" to alter the constitutional ban.

Carpenter said that he was having private conversations with Republican members who might support the bill, but quipped that he did not want to “out” them as potential allies.

Nevertheless, he said, the group gathered with him Thursday is “on the right side of history,” supported by younger voters who overwhelming favor same-sex marriage and will eventually make it a reality nationwide.