Democratic presidential candidate Joe Biden narrowly won the Washington state primary, keeping a lead over progressive Sen. Bernie Sanders, according to The Associated Press.

Washington was one of six states that voted last Tuesday — including Michigan, Missouri, Mississippi, North Dakota and Idaho — but was the last to have a winner declared Monday evening. Washington votes entirely by mail-in ballots.


Biden secured victories in all states except North Dakota, which went to Sanders. His Washington win continues a surge for the former vice president that initially started with a rocky trail behind Sanders.