Charleston businessman Martin Skelly, who was seeking the 1st Congressional District seat, has dropped out of the race and endorsed fellow Democrat Elizabeth Colbert Busch.
That leaves just Busch and perennial Democratic candidate Ben Frasier running for the nomination.
In a press conference Monday, Skelly said he wants to help unite the party going into the special election.
Sixteen Republicans are also vying for the seat, left open when Gov. Nikki Haley appointed Tim Scott to South Carolina's open U.S. Senate seat. The primary is March 19.