Graham was critical of Trump's recent derogatory comments about Mexican immigrants and calls the issue a "defining moment" for Republicans. He says on CNN's "State of the Union" that if the GOP doesn't reject Trump's views, "we will have lost our way."
In a weekend appearance in Phoenix that drew thousands, Trump repeated his assertions that Mexico was sending violent offenders to the U.S. to harm Americans.
Trump's words are worrisome to Republicans, who fear the outspoken businessman is hurting the party's standing with the nation's surging Latino population before voting begins in the 2016 presidential primaries.