How the Senate is taking Lindsey Graham's presidential ambitions

“He’s my man,” says Arizona Republican Sen. John McCain, who won his party’s endorsement in 2008 and knows his way around Iowa and New Hampshire. “He’s a dark horse. Keep an eye on him.”

Graham’s formal launch Thursday of a political committee “Security Through Strength” left some on Capitol Hill scratching their heads. A few of his colleagues chuckled when asked in the marbled hallways what they thought of the defense hawk embarking on a serious presidential campaign.

Graham, who is known as a hardworking legislator, but not a senator with gravitas, is testing the waters at a time when the 2016 field is already packed with potential. The 2016 GOP primary could have a host of past and present GOP governors, from Scott Walker to Mitt Romney to Jeb Bush to Chris Christie. And many of Graham’s colleagues, including Sens. Marco Rubio, R-Fla., Rand Paul, R-Ky., and Ted Cruz, R-Texas, have already been laying the groundwork for their own campaigns for months.