Washington (CNN) Sen. Lindsey Graham may be languishing in the bottom of GOP presidential primary polls, but on Thursday he delivered a sharp rebuke of his GOP opponents before a Republican Jewish audience.

"The one thing I can tell you is that what Mr. Trump's saying about how to handle this war is empowering the enemy," Graham said, referring to GOP front-runner Donald Trump's recent assertion that the U.S. should "go after" the families of terrorists.

"ISIL loves Donald Trump because he is giving them an opportunity to bring people their way," Graham said during a gathering with reporters following his formal speech to the Republican Jewish Coalition.

Also among the digs: He guaranteed that Republicans will lose the race for the White House if they nominate his opponents like Donald Trump and Sen. Ted Cruz.

The South Carolinian spoke just after the Texas Republican senator, and declared himself so frustrated with Cruz's speech that he deviated from his prepared remarks.

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