Both of Washington’s Democratic U.S. senators, Patty Murray and Maria Cantwell, are considered swing votes in the upcoming battle to repeal the estate tax. Today, the Campaign for America’s Future, a liberal D.C. group, targeted both senators in a full-page ad in Rollcall, D.C.’s newspaper devoted to Capitol Hill. Last week, a conservative group ran a TV ad depicting Cantwell as a vulture. Tomorrow, liberal groups hold a press conference to encourage Murray and Cantwell to support the tax that only is levied on around one percent of estates.Why are our two senators at the center of this national debate? One obvious reason is that Frank Blethen, the publisher of The Seattle Times whose family owns a controlling interest in the state’s largest and most powerful newspaper, has been aggressively campaigning to repeal the estate tax for years. He seems to have gotten through to a couple of people.