It's a minor win for Sanders: West Virginia awards delegates proportionately, and while votes are still being counted, he's unlikely to win by enough percentage points to significantly dent Clinton's lead in the delegate race.
Sanders was expected to do well in West Virginia, where voters are largely white and working class. He also likely benefited from the state's primary system, which allows independent voters to vote in either the Democratic or Republican election. More than 250,000 West Virginia primary voters were unaffiliated, according to state data.
Ahead of Tuesday's primary, Clinton led Sanders in the pledged delegate race by about 300 delegates. Counting unpledged delegates, also known as superdelegates, Clinton is ahead by more than 700. Sanders' team has acknowledged the mathematical hurdles to overtaking Clinton in the pledged delegate race, and has instead shifted its strategy to challenging the former secretary of state at the convention.
"She will need superdelegates to take her over the top," Sanders said last week of Clinton's path to victory. "The convention will be a contested contest."
Next Tuesday, Democratic voters head to the polls in Kentucky and Oregon. The rest of the Democratic primaries, including California's and New Jersey's, will take place in early June.