Biden led Sen. Bernie Sanders (I-Vt.) in the popular vote in the state for nearly a week as the votes were counted. Sanders won more than two-thirds of the delegates from the Washington caucuses over Hillary Clinton in 2016.
Under Washington state’s primary rules, 31 of the state’s 89 pledged delegates are allocated based on the statewide result. The remainder is decided based on the results of individual congressional districts. Those results might not be calculated until the election is certified by the secretary of state’s office, which could be as late as March 27.
Biden also won Missouri, Mississippi, Michigan, and Idaho on March 10, securing a significant delegate lead over Sanders, who won North Dakota.
Washington Democrats used the vote-by-mail presidential primary format for the first time this year. The state used to hold smaller caucuses in the May time frame in prior years.
The results from Washington arrived as Biden and Sanders were about to face off in the populous states of Arizona, Illinois, and Florida on March 17. Ohio, which was also scheduled to hold a primary on March 17, postponed the election until June 2 over concerns about the spread of the coronavirus pandemic.
Polls conducted in the four states voting on March 17 show Biden in the lead by a wide margin.
Biden is well ahead of Sanders in the pledged delegate count. The former vice president also leads Sanders by more than 20 points in the average of polls maintained by Real Clear Politics.
Illinois and Florida reported a surge in early voting ahead of the primary.
Illinois had 504,000 early votes cast and 294,000 ballots mailed in as of March 16—outpacing the numbers from the 2016 primary when the state recorded 400,000 early votes and 160,000 mail-in ballots.
A state official in Florida told The Associated Press that 1.1 million Democratic ballots had been cast by mail or at early voting centers through March 15. About 890,000 Democrats voted early in the 2016 primary.
Prominent leaders and groups in the Democratic Party have been coalescing around Biden. On March 16, he picked up endorsements from Illinois Gov. J.B. Pritzker and the International Longshoremen’s Association, a large maritime workers’ union based in New Jersey. The nation’s largest union, the National Education Association, endorsed Biden on March 14.
Sanders and Biden represent competing wings of the Democratic party. Sanders, a self-described socialist, is the leader of the party’s hard-left, progressive wing. Biden, who is seen as the moderate choice, has shifted further left during the primary.
The Associated Press contributed to this report.