(CNN) Former Vice President Joe Biden will win the Washington state Democratic presidential primary, CNN projected Monday.

CNN's delegate estimate in the state currently shows Biden tied with Vermont Sen. Bernie Sanders , each winning 30 delegates, with 29 left to be allocated.

The projection comes nearly a week after the state's primary. All of the state's voting is done by mail, which can extend the time it takes to report results.

Biden leads in the overall delegate count after a run of primary victories. Last week, Biden won the key Midwest swing state of Michigan , in addition to Idaho Missouri and Mississippi . Sanders won in North Dakota

Sanders said he would remain in the presidential race, despite the string of defeats having significantly narrowed his path to getting enough delegates to win the party's nomination.