Democratic U.S. Sen. Patty Murray of Washington will face Republican challenger Dino Rossi in November.
Murray and Rossi advanced Tuesday through Washington's "top two" primary, an unusual system that lists all candidates on the same nonpartisan ballot and sends the two highest vote-getters to the fall ballot.
Murray is considered vulnerable in her bid for a fourth term. She welcomed a primary-day visit from President Barack Obama to boost her momentum and campaign checkbook.
Rossi is a former state lawmaker who lost two close bids for governor.
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