Since Marshall was first elected in 1991, the district, which covers Manassas and Prince William County, has become more populous, diverse and left-leaning politically. In November, it was one of 17 Republican-controlled House districts Hillary Clinton won over Donald Trump in the presidential race.
“The district is changing … and at some point he’s likely to be defeated,” University of Mary Washington political science professor Stephen Farnsworth said. “We’ll see depending on the campaign whether this year is that year.”