Activists Robin Tyler (L) and her partner Diane Olson chant during a rally outside the Beverly Hilton hotel, where U.S. President Barack Obama was attending a Democratic party fundraiser, in Beverly Hills, California May 27, 2009. Two lawyers who squared off in the legal battle over the 2000 U.S. presidential election teamed up on Wednesday to challenge California's gay marriage ban in a move that, if successful, would allow same-sex couples to wed anywhere in the United States. The lawsuit, filed on behalf of two same-sex California couples barred from marrying under the voter-approved ban known as Proposition 8, puts them at odds with gay rights advocates who see a federal court challenge as too risky and fear a loss in the U.S. Supreme Court. REUTERS/Mario Anzuoni (UNITED STATES POLITICS CONFLICT)