South Carolina Gov. Nikki Haley (R) will announce the replacement to Sen. Jim DeMint (R-S.C.) at noon on Monday.
Haley will make the announcement at the Statehouse, according to the Associated Press.
The appointment Haley will make will hold the seat until a special election in 2014 when South Carolina voters will decide who will finish the last two years of DeMint's term.
South Carolina Republican Reps. Tim Scott and Trey Gowdy have regularly been mentioned as possible replacements for DeMint.
DeMint has indicated himself that he would like Scott to take his seat. But last week the senator said he had not been in touch with Haley since announcing he would leave the Senate.
“I’ve not called her since, and I’m not pressuring her in any way,” said DeMint. “I’m convinced we share the same philosophy. We have a great congressional delegation, and I hope she looks at those folks,” he added.
Former South Carolina Attorney General Henry McMaster (R) and Catherine Templeton, who heads the state’s Department of Health and Environmental Control, were also said to be on Haley’s shortlist.
According to CNN, however, Haley notified McMaster on Sunday night that he would not be picked to replace DeMint.
This story was updated at 9:05 a.m.