McDermott won his last general election with 80 percent of the vote, but he had already attracted one primary challenger in his safe Democratic 7th District before the holiday recess. State Rep. Brady Walkinshaw announced his candidacy in early December, promising to be the “region’s next progressive leader.†The Democratic field in this Seattle-based district is expected to grow with McDermott out. Thanks to Washington’s top-two primary system, the general election could pit two Democrats against each other. Former Massachusetts Gov. Mitt Romney and Arizona Sen. John McCain each received just 18 percent of the vote in this district in...