The national board of Log Cabin Republicans voted 22-2 Tuesday night to hold back the endorsement and called Mr. Bush "disloyal" to the 1 million gay men and lesbian women who it said supported his candidacy four years ago.
"It is impossible to overstate the depth of anger and disappointment caused by the president's support for an antifamily constitutional amendment. This amendment would not only ban gay marriage, it would also jeopardize civil unions and domestic partnerships," Log Cabin political director Chris Barron said.
The organization said significant victories for gay rights marked the early days of the Bush administration, including the appointment of openly gay employees in the administration and anti-discrimination protection for federal employees.
Log Cabin executive director Patrick Guerriero said the administration shifted from initial reluctance over a ban on same-sex marriage to full support after the campaign decided to focus its re-election efforts on persuading evangelical Republicans who stayed at home in 2000 to go to the polls this year.
"Log Cabin's decision was made in response to the White House's strategic political decision to pursue a re-election strategy catered to the radical right. The president's use of the bully pulpit, stump speeches and radio addresses to support a constitutional amendment has encouraged the passage of discriminatory laws and state constitutional amendments across America. Using gays and lesbians as wedge issues in an election year is unacceptable to Log Cabin," Guerriero said.
The group also denounced what it called "the continued flip-flops on gay and lesbian issues" by Democratic nominee John Kerry. It said Kerry has repeatedly made clear his opposition to civil marriage equality and has supported discriminatory constitutional amendments in Massachusetts and Missouri.
Kerry has said he opposes a constitutional amendment banning gay marriage, calling it a matter for states to decide. He has said he supports civil unions.