Meanwhile, Republican Donald Trump also won there and in Nebraska, a week after he cleared the field of his remaining rivals. They were not victories likely to heal the party's wounds, as some GOP leaders continue to hold off offering their endorsement of the party's presumptive nominee.
The result in the West Virginia Democratic primary yesterday underscored the awkward position Clinton and the party's establishment face as they attempt to turn their focus to the general election. Clinton is just 155 delegates short of the 2,383 she needs to secure the nomination. To win them, she needs just 17 per cent of the delegates at stake in the remaining contests.
Still, Sanders is vowing to fight on. He campaigned in California yesterday for the state's June 7 primary, and his victory in West Virginia highlighted anew Clinton's struggles to win over white men and independents weaknesses Trump wants to exploit in the fall campaign.
Among those voting in the state's Democratic primary, about a third said they would support Trump over either Clinton or Sanders in November.
While Sanders is still attracting thousands to rallies, his campaign has grown harder as Clinton closes in on the nomination.
His fundraising has fallen off and so, too, has his advertising, with only about USD 525,000 in ads planned for California and USD 63,000 each in West Virginia and Oregon, according to advertising tracker Kantar Media's CMAG.