Support from this group of lawmakers reflects Paul’s outsider, anti-establishment message—and illustrates the importance of enlisting well-connected supporters in critical early nominating states.

There’s is speculation that Sanford won’t be the only official from South Carolina—home of the third Republican nominating contest in 2016—to back Paul. According to GOP sources, Reps. Mick Mulvaney and Jeff Duncan, both favorites of the most conservative wing in Congress and in their home state, are seen as leaning toward endorsing Paul. (Both Mulvaney and Duncan denied that they’ve made up their minds, although Mulvaney said he shot a video for his “buddy” Paul that will be shown at Thursday’s Charleston event.)

“They are very popular and could play a big role around the state,” Mallory Factor, a top Paul organizer in South Carolina, said of Mulvaney and Duncan. “If those guys were to support him for president, it would contribute a lot to Senator Paul potentially winning South Carolina.”