Rep. Keith Ellison (D-Minn.) says that Trump’s rhetoric could provoke violence.
The new ad will air in Iowa and New Hampshire.
Carson, who had been in first place last month, fell to third in the latest Quinnipiac poll.
Those polled also favor sending American ground troops to fight ISIS.
Trump lambasted the media for not showing the entirety of the crowds watching his speeches.
Donald Trump tells reporter everyone knows he has world's best memory.
Bush now has 26 House members in his corner, as well as three senators.
Hip-hop star Killer Mike introduced Sanders at a rally Monday in Atlanta.
Carson "was mistaken" in saying he had seen film of U.S. Muslims celebrating, an aide said.