Lindsey Graham is dropping out

Sen. Lindsey Graham, R-S.C., is dropping out of the 2016 presidential race.

In an email announcing his decision, Graham wrote that he believes his campaign made enormous progress in turning back the "tide of isolationism" in the Republican Party.

"While we have run a campaign that has made a real difference, I have concluded this is not my time," Graham wrote in an email announcing his departure on Monday. "I want to thank you for standing with me. More than you will ever know, you have honored me with your support. I hope we have run a campaign in which you have been proud. I know I am, and I know that together we have won an important contest of ideas."

In an interview with CNN announcing his departure from the 2016 race, Graham acknowledged that he "hit a wall," but added that he thinks the eventual GOP nominee will adopt his plan to defeat the Islamic State. Monday, Dec. 21, was the deadline for Graham to keep his name off the ballot in South Carolina.