“If we can’t get a good deal—a balanced deal that calls on the wealthy to pay their fair share—then I will absolutely continue this debate into 2013 rather than lock in a long-term deal this year that throws middle-class families under the bus,” Mrs. Murray said, in what sounded like an ultimatum.

That bit about throwing middle-class taxpayers “under the bus” is political spin, because Republicans say they’re ready to vote to extend for another year the current tax rates on all taxpayers, including everyone who makes less than $250,000. The Murray Democrats are the ones holding the middle-class rates hostage to a GOP vote to raise taxes on the affluent.

Mrs. Murray was more honest in explaining her political calculations. “If the Bush tax cuts expire, every proposal [in 2013] will be a tax cut proposal, and the [GOP's anti-tax increase] pledge will no longer keep Republicans boxed in and unable to compromise,” she said.

“If middle-class families start seeing more money coming out of their paychecks next year—are Republicans really going to stand up and fight for new tax cuts for the rich? Are they going to continue opposing the Democrats’ middle-class tax cut once the slate has been wiped clean? I think they know this would be an untenable political position.”

So there you are. Democrats are delighted to let a giant tax increase whack the economy in January because then Republicans won’t be able to stop it and will also find it impossible to cut taxes again on anyone whom Democrats define as “the wealthy.”

Mrs. Murray may think she’s putting Republicans on the political spot, but her real hostage is the already weak economy. …