A Democratic congressional pick-up in a coastal South Carolina special election? With a Democrat like high-profile Elizabeth Colbert Busch facing a Republican like baggage-laden former Gov. Mark Sanford, it's possible. When he won the GOP primary run-off Tuesday, Sanford notched another step toward a political comeback, years after he became best known as the man who made "hiking the Appalachian Trail" code for philandering. But even though he spent three terms representing the 1st Congressional District in the 1990s, he faces a tougher than usual challenger in Colbert Busch — and in his own political career, which ground to a halt in 2009 with a cheating affair and ethics scandal. Colbert Busch's campaign's own internal poll showed her leading by three points, within the margin of error but remarkable in a district Mitt Romney won by 18 points last year. On "Morning Joe" Wednesday, Sanford attributed her strong poll number to his tough GOP primary, but still, the GOP isn't taking any chances. It is attacking Colbert Busch for remaining on-staff at Clemson University while she campaigns, while Democrats are citing Sanford's 2009 refusal to step down, as his party had asked, as indicative of poor judgment.