SEATTLE – President Barack Obama wasted little time casting Republican rival Mitt Romney as “backwards on equality” on Thursday, eager to transform his historic embrace of same-sex marriage into donor enthusiasm and grassroots vigor.

Just one day after announcing his support of the top gay rights issue, Obama was attending a lavish West Coast fundraiser hosted by actor George Clooney in Los Angeles’ Studio City area, the heart of celebrity gay marriage activism.

At the same time, his campaign rolled out a Web video claiming Romney would roll back some rights for same-sex couples

White House spokesman Jay Carney brushed aside questions about the timing of the attack on Romney, saying that Obama and Romney had differed on issues of gay rights even before the president declared his support for same-sex marriage.

“Gov. Romney is for an amendment to the U.S. Constitution that would enshrine discrimination into our founding legal document,” Carney said.

“The president thinks that’s wrong. So their positions were starkly different before yesterday.”