WASHINGTON —  A conservative group in Virginia said Tuesday it would oppose Supreme Court nominee John Roberts' (search) confirmation because of his work helping overturn a Colorado referendum on gays.

The stance by Public Advocate of the United States, which describes itself as a pro-family organization, puts it in opposition to conservative groups that have endorsed Roberts. A number of liberal groups oppose President Bush's nominee.

"The move comes as a result of Roberts' support for the radical homosexual lobby in the 1996 Supreme Court case Romer v. Evans, which overturned a pro-family law passed by the citizens of Colorado in an appalling act of judicial activism," the group said in a news release. It planned a news conference for Wednesday in front of the Supreme Court.

The group's president, Eugene Delgaudio, had said last week that if "Judge Roberts did provide advice on how to overturn this pro-family measure overwhelmingly supported by the people of Colorado, then Public Advocate calls on President Bush to withdraw his nomination of Judge Roberts immediately."

Messages left for Delgaudio seeking comment were not immediately returned on Tuesday.

This is not the first time Delgaudio has gone up against the Bush administration. He criticized Vice President Dick Cheney last year after the vice president, when asked about gay marriage, said, "Freedom means freedom for everyone."

Delgaudio said then: "'Freedom' is not embracing perversion."

The Colorado gay rights case involved Amendment 2, a constitutional amendment approved by voters in 1992 that would have barred laws, ordinances or regulations protecting gays from discrimination by landlords, employers or public agencies such as school districts.

Gay rights groups sued, and the measure was declared unconstitutional in a 6-3 ruling by the U.S. Supreme Court in 1996.

Roberts' role in the case included helping develop a strategy and firing tough questions during a mock court session at Jean Dubofsky, a former Colorado Supreme Court justice who argued the case on behalf of the gay rights plaintiffs.

Other conservative groups, including the Traditional Values Coalition and Focus on the Family Action, the political arm of the Colorado Springs-based conservative Christian ministry Focus on the Family, are still supporting Roberts.

"We support President Bush and his choice for the Supreme Court, John Roberts," said the Rev. Lou Sheldon, founder of the Traditional Values Coalition.

Other groups also are taking public stands on Roberts' candidacy.

NARAL Pro-Choice America plans to start running television ads opposing Roberts on Wednesday, and other abortion rights groups including the National Organization for Women, the National Abortion Federation and the Feminist Majority all have announced their opposition to Roberts.

The National Association of Manufacturers, led by Republican John Engler, is expected to announce an endorsement of Roberts on Wednesday.