Jim DeMint

GOP holds on to House seat, but Dems surpass expectation

Republicans held onto Mick Mulvaney's South Carolina congressional seat in Tuesday's special election, but the 3-point margin was hardly what they may have been presuming, given Mulvaney's 20-point victory in November.

Why - and how - did Democrats outperform expectations in South Carolina, where all statewide officers are Republicans, and six of the seven U.S. House seats are, too?

It could be in part because the national party largely stayed out of the race.

The Democratic Congressional Campaign Committee funneled $5 million into Georgia's 6th District, where voters also selected a Republican on Tuesday in what became seen as a test for Republican strength in the...