PALM BEACH, Fla. (AP) — Republican presidential candidates Marco Rubio and John Kasich suggested Saturday they may not support Donald Trump if he becomes the GOP nominee, as violence at the front-runner's rallies deepened the party's chaotic chasm.Rubio told supporters that while he was currently sticking with his pledge to back the nominee if he wasn't the party's choice, "it's getting harder every day."Kasich said the "toxic environment" Trump is creating "makes it very, extremely difficult" to support him."To see Americans slugging themselves at a political rally deeply disturbed me," Kasich said while campaigning in Cincinnati.