WASHINGTON — A group of atheists, led by a California man known for challenging the use of the words "under God" in recitals of the Pledge of Allegiance at public schools, filed a lawsuit Tuesday to bar prayer and references to God at the swearing-in of Barack Obama as president.

Michael A. Newdow, 17 other individuals and 10 groups representing atheists are suing Supreme Court Chief Justice John Roberts, several officials in charge of inaugural festivities, the Rev. Joseph Lowery and megachurch pastor Rick Warren. They filed the complaint in U.S. District Court.

Newdow failed in similar lawsuits to remove prayer from President Bush's swearing-in ceremonies in 2001 and 2005.

Roberts will administer the oath of office to Obama at the Jan. 20 ceremony. Warren and Lowery will deliver the invocation and benediction, respectively.

Newdow and others also argue that the phrase "so help me God," used in inaugural oaths since the swearing-in of President Franklin D. Roosevelt, should be stricken, saying it is not part of the oath as specified in the Constitution.

Bob Ritter, staff attorney for the American Humanist Association and counsel for the suit, said the group can win "as long as the judges uphold the Constitution."

"We think the law is on our side," he said.

Ritter said the lawsuit targets the oath, the invocation and the benediction.

According to the lawsuit, the opening and ending prayers "are completely exclusionary, showing absolute disrespect to Plaintiffs and others of similar religious views, who explicitly reject the purely religious claims that will be endorsed, i.e., (a) there exists a God, and (b) the United States government should pay homage to that God."

The legal move is the latest controversy over the inauguration. Gay-rights advocates and liberal groups are outraged by Obama's selection of Warren, who endorsed the new ban on gay marriage in California.

Conservatives, meanwhile, criticize Warren for agreeing to appear at the inauguration.

Scott Walter, executive director of the Becket Fund for Religious Liberty, called the lawsuit a "publicity stunt," in a statement Tuesday. The Becket Fund promotes free expression of religion and has opposed Newdow's efforts to curb the Pledge of Allegiance in schools.

"Newdow's lawsuit over the inauguration is a lot like the streaker at the Super Bowl: a pale, self-absorbed distraction. And anybody who looks at it carefully can see there's not much there," Walter said.