NORTH CHARLESTON, S.C. — Jeb Bush on Friday joined his super PAC’s attack on Marco Rubio’s character, saying that the Florida senator “cut and run” from his past support for comprehensive immigration reform.

Bush was appearing with Lindsey Graham to accept the South Carolina Republican’s endorsement for president when he was asked if he is comfortable with a tough attack ad aired by his super PAC, Right to Rise USA, that accuses Rubio of flip-flopping on immigration. Strategists for the group have described the spot as primarily a hit on Rubio’s “character,” rather than on his immigration policy, and Bush, the former Florida governor, is now echoing the hit.