Graham is one of the most hawkish figures in the GOP.

He has been one of the loudest critics of President Obama's foreign policy, insisting on more forceful military actions in Syria and Iraq and warning about the dangers of negotiating with Iran. In a recent joint statement with Sen. John McCain (R-Ariz.), he called hopes that an Iranian nuclear deal would curb the threat the country poses "simply delusional." While much of the Republican field is in the hawkish wing of the GOP, Graham could face resistance in from war-weary primary voters and activists led by Sen. Rand Paul (R-Ky.).

Graham has clashed with the tea party. 

Graham has long clashed with conservative activists. “The problem with the tea party, I think it’s just unsustainable because they can never come up with a coherent vision for governing the country. It will die out," he told the New York Times Magazine for 2010 story. His support for comprehensive immigration reform and his votes to confirm Obama's Supreme Court nominees have infuriated some activists. But when the tea party tried to unseat him in the 2014 primary, Graham had the last laugh as the movement failed to coalesce around a single alternative candidate and Graham cruised to reelection.

Graham likes to go on the Sunday news shows. A lot.

If you turn on your TV on any given Sunday morning, there's a decent chance you'll see Graham. The Upshot analyzed data collected by American University and found that between 2009 and the fall of 2014, Graham made 85 (!) appearances on Sunday shows. Only his good friend, Sen. John McCain (R-Ariz.), appeared on the show more.

He claims to have never sent an email.

Seriously. He recently said so during -- where else -- a Sunday show appearance.

He's a fan of Richard Pryor and Jonathan Winters.

Graham likes "situational humor," he explained to Bloomberg Politics earlier this year.