"The attorney general of the United States should be impeached over his repeated lawlessness in attempting to impose same-sex marriage throughout the nation," the Rev. Bill Owens, president and founder of the Coalition of African American Pastors, said in a release posted on the organization's website.
"It's one thing to make a political argument that gay marriage should be the law, but it's quite another to take actions that ignore federal law, Supreme Court rulings and the constitutions of dozens of states that have specifically rejected the redefinition of marriage which the administration is trying to impose."
The group said it is starting a grassroots effort to collect 1 million signatures on an impeachment petition.
"As much as President Obama and Attorney General Holder would like it to be otherwise, we live in a democracy -- with government of, by and for the people -- not a monarchy ruled by a king issuing decrees from on high," Owens said. "The citizens of several states who have voted overwhelmingly to preserve marriage have had their votes voided and thrown out by radical federal judges; and the Obama administration -- in particular the Justice Department -- has been shamefully complicit in this attack on the rights of those voters."
The impeachment effort came as Holder said state attorneys general have no obligation to defend laws they believe are unconstitutional.
The comments by Holder, who was to address the National Association of Attorneys General Tuesday, were made in the wake of decisions by six state attorneys general to refuse to defend bans on same-sex marriage, the New York Times reported Monday.
Holder said such decisions were "appropriate" for an attorney general to make.
He equated campaigns for equal rights for gays to the civil rights struggle of the 1960s, calling gay rights one of the "defining civil rights challenges of our time."
"If I were attorney general in Kansas in 1953, I would not have defended a Kansas statute that put in place separate-but-equal facilities," Holder added, referring to the Brown vs. Board of Education ruling by the Supreme Court that struck down segregated schools.
Holder's remarks drew an immediate rebuke from Attorney General J.B. Van Hollen of Wisconsin, where four same-sex couples have sued to overturn the state's ban on gay marriage.
"We are the ultimate defenders of our state constitutions," said Van Hollen, a Republican. "There is no one else in position to defend the state Constitution if it comes under attack."
State attorneys general in Nevada, Oregon, Pennsylvania and Virginia have chosen not to defend bans on same-sex marriage. Attorneys general in California and Illinois declined to defend bans that were ultimately overturned.