Likely D. If Stewart doesn't galvanize conservatives enough, former Virginia Attorney General Ken Cuccinelli could enter the race as well.
Virginia Rep. Barbara Comstock should run, but she is one of the most vulnerable House Republicans in 2018, just like how Missouri Rep. Ann Wagner's seat could be vulnerable, and Michigan Rep. Fred Upton's seat could be vulnerable.
However, the most electable Virginia Republicans could be Ed Gillespie, if he fails at the 2017 VA GOV, and Eric Cantor, despite his Beltway insider baggage.
I almost think running statewide could be easier than retaining her House seat.
Her district is rapidly trending Dem. She might hold on, but it'd be close.