Unlike many southern states, Virginia has always had a vigorous Republican Party. At first it was based in the mountains and hills east of the Blue Ridge Mountains, where there were few blacks and little historical support for slavery (there was an additional ancient base among blacks that, when combined with western Virginia, made Republicans competitive statewide into the late 1800s; this was wiped out by the poll tax in 1902). They also began carrying Arlington County in the northeast as early as the 1920s, establishing a second toehold in the soon-to-be-growing northern Virginia suburbs. The addition of the third base made Republicans a majority when conservative Byrd Democrats finally exited the Democratic Party and began voting Republican.

But during the 1990s and 2000s, Bill Clinton's socially moderate, fiscally conservative message allowed him to become the first Democrat since LBJ to run even in northern Virginia. As the Democratic Party continued to embrace a relatively fiscally conservative stance, the northern suburbs continued to gravitate toward the Party of Jackson.  This trend was epitomized in 2006, when former Republican Gov. George Allen lost to Jim Webb, a relatively obscure Democratic opponent, largely on the basis of Webb's strong performance in northern Virginia.  While Allen's fateful utterance of the word "macaca" is remembered as the incident that began his decline, in truth he was below 50 percent in the polls before that event, and Webb's fundraising was already picking up.

Webb decided to retire in 2012, and former governor Tim Kaine held the seat for the Democrats against Allen.  The state has continued to shift toward the Democrats, who nearly recaptured the House of Delegates during the 2017 elections, but Republicans have a competitive primary for this senate race.  Two populist candidates, former Lieutenant Gov. nominee E.W. Jackson and Prince William County Council Chart Corey Stewart, may end up splitting the vote, opening up an opportunity for the Del. Nick Freitas, a more “establishment” candidate, to sneak up the middle.  Regardless of the outcome, Kaine starts out as a favorite here.