I hadn't mentioned this before, but I spoke with someone at the CA Republican convention who had worked for Carl DeMaio's congressional campaign. He told me some social conservatives said they wouldn't vote for DeMaio because he was gay. They reasoned that DeMaio winning or losing wouldn't change whether the GOP had the majority. So the party wouldn't be losing anything by DeMaio losing. Pastor Jim Garlow of Skyline Church, a Republican, has decided to not only not support DeMaio, but endorse his Democratic opponent Congressman Scott Peters.
This operative didn't indicate that any of those people would endorse Peters, but that endorsement puts Peters in an odd situation. Peters can't exactly embrace the homophobe vote. He'd look like a homophobe himself and that's not going to help him at all. This pastor's public endorsement of Peters cuts both ways for DeMaio. On the one hand, it could inform some social conservatives that DeMaio is gay and that they should oppose him. DeMaio could lose some votes, although I think they sort of people who would oppose DeMaio for being gay aren't going to vote for a Democrat. They are likely to leave the race blank.
On the other hand, this public opposition really undercuts Peters' big criticism of Carl DeMaio, that DeMaio is a "Tea Party extremist." Peters has been using this line of attack for the last year. If DeMaio is the focus of homophobia, Peters will look like he's lying with this attack. While this rhetoric may hurt DeMaio with social conservatives, he might win more of the LGBT vote. Nothing says "you're one of us" quite like people hating you for being gay. Supporting DeMaio, even if they might disagree with him on some issues, is a way to stand against homophobia. Likewise criticism from the far right could help DeMaio with moderates who feel he's being unfairly attacked.
While this pastor is endorsing Peters, right wing social conservatives are far more likely to vote for no one than jump to Peters. On the other hand, every moderate or LGBT vote DeMaio gets is one less Peters gets. Thus, the votes DeMaio gains in the middle are worth double the ones he loses on the right.
I've said all along that the anti-gay sentiment wouldn't sink DeMaio, as it didn't sink his mayoral bid. I could be wrong and this could be a difference maker. I do, however, think announcements like this might help DeMaio more than hurt him.