Washington (CNN) - Vice President Joe Biden will attend a South Carolina Democratic dinner the weekend before a special election to fill a vacant congressional seat in the state, a source familiar with his plans told CNN, though he doesn't plan to campaign for the Democratic candidate Elizabeth Colbert Busch.
Colbert Busch will face off against either former congressman and governor Mark Sanford or former Charleston County Councilman Curtis Bostic in the May 7 general election for the 1st Congressional District.
She won the Democratic nomination this week while the Republican candidate - either Sanford or Bostic - will be decided in an April 2 runoff.
The dinner is a fundraiser for the South Carolina Democratic Party. Biden will not be in the first district during his trip to the Palmetto State, and Colbert Busch is not attending the dinner, according to her campaign.
Colbert, a satirist and host of a Comedy Central show, campaigned on his sister's behalf.
"She's my sister, and I'm willing to, you know, break the jewel of my own creation to try to do something for her," Colbert told CNN Chief Washington Correspondent Jake Tapper this week on CNN's "The Lead."
Colbert Busch, an official with Clemson University's wind turbine drive testing facility, is expected to have an uphill climb because the district is heavily Republican and one in which Mitt Romney won by a larger margin than he did in the state as a whole.