U.S. Sen. Tim Scott, R-North Charleston, has nearly $3.1 million to spend, after raising more than $430,000 from October through December.
Scott has raised more than $4 million total for his bid to keep the U.S. Senate seat. S.C. Gov. Nikki Haley appointed Scott to the seat after then-U.S. Sen. Jim DeMint resigned to lead the conservative Heritage Foundation.
Scott faces no Republican challengers in June's primary, but two Democrats have announced plans to run against him: Rick Wade, formerly an Obama campaigner, adviser and deputy chief of staff for the U.S. Commerce Department, and Richland County Councilwoman Joyce Dickerson.
Brandon Armstrong of Mount Pleasant has said she plans to run as an independent.
Scott is South Carolina's first black U.S. senator. Before being appointed to the seat, he represented the state's 1st District congressional seat.