By Keith Coffman
DENVER (Reuters) - Colorado legalized same-sex civil unions on Thursday, reflecting a recent shift to the left in the political balance of power in the Denver statehouse.
Democratic Governor John Hickenlooper signed the measure that backers say makes gay and lesbian couples eligible for the most of the same benefits, protections and responsibilities currently extended only to heterosexual spouses.
However, Colorado still bans gay marriage and is one of 30 states with a constitutional amendment that defines marriage as exclusively between a man and a woman.
When the law takes effect May 1, Colorado will join eight states that recognize civil unions or domestic partnerships in lieu of gay marriage, according to the Human Rights Campaign.
Gay rights advocates thanked Hickenlooper for his "courage and leadership" in enacting the law, which they said gave the state's same-sex couples and their families access to critical legal protection.
"This historic victory belongs to the thousands of loving, committed couples across the state who have worked tirelessly for years to make it possible for their families ... to have these important legal safeguards," said Brad Clark, executive director of gay and transgender advocacy group One Colorado.
"For them, this moment was long overdue," he added.
The Catholic archbishop of Denver, Samuel Aquila, said the passage of the law was an effort to redefine marriage and family.
"Marriage is a stabilizing institution at the foundation of civil society. Religious liberty is a civil rights issue," he said. "Today both have been grievously harmed. Today our state and federal constitutions have been dealt a troubling blow."
Another nine states and the District of Columbia have legalized same-sex marriage. Among those states, Washington state, Maine and Maryland in November became the first in the nation to approve gay marriage at the ballot box.
Republicans, who previously controlled the lower house of Colorado's General Assembly, foiled passage of similar legislation during the past two years.
But Democrats gained a House majority in November's elections, giving them the votes needed to pass a civil unions bill earlier this month, after Hickenlooper opened the legislative session in January by urging passage of such a measure.
(Reporting by Keith Coffman; Editing by Cynthia Johnston and Lisa Shumaker)