A Republican senator's embrace of gay marriage is the latest sign of soul-searching in a party struggling with society's fast-changing views on emotional issues.
Gay marriage still divides the party, with the conservative wing strongly opposed. But an increasing number of Republicans are reversing course.
The latest is Sen. Rob Portman of Ohio.
He says his change took a lot of thought and began after he learned one of his sons is gay.
Portman is one of the GOP's more prominent members. He is a former U.S. trade representative and White House budget director. Mitt Romney considered him as a running mate. He is the first Republican senator to openly back gay marriage.
Some conservatives say they feel betrayed by his shift. But many are responding with a shrug.