Politicians passed an ordinance that strengthens the rights of gay and lesbian couples despite a congressional backlash that could cost the city millions of dollars.

The ordinance - passed without a hint of objection - will make San Francisco the nation's only city that demands private businesses offer domestic partners the same customer discounts they extend to married couples. Mayor Willie Brown says he will sign it.Most businesses that might be subject to the law, such as gyms, car rental companies and insurance agencies, already comply. Still, supervisors were determined for the city to set a standard for human rights.

Monday's vote comes despite what gay rights advocates are calling an anti-gay campaign in Washington.

Less than two weeks ago, the House voted 214-212 to block the city from receiving federal housing money because of its year-old Equal Benefits Ordinance, which requires businesses with city contracts to extend health benefits to its workers' partners. The measure, which still has to be approved by the Senate, could cost San Francisco up to $260 million.

"We should not force or coerce (businesses) to adopt policies they find morally objectionable," said Rep. Frank Riggs, a Republican with a mostly rural constituency in northern California.

Democrats attacked Riggs' proposal as mean-spirited and bigoted. "I don't know why Mr. Riggs wants to create a war," said Rep. Nancy Pelosi, who represents San Francisco.

Despite the Riggs measure, Monday's expansion of the domestic partner benefits law caused hardly a flutter in the city. It has faced little opposition from business owners. Supervisor Mark Leno, who introduced the measure in June, could not name a company in the city that would have to change its ways.