Specifically, they're not actually going to vote down the Senate bill directly. Instead they will vote on a single measure that rejects the Senate's plan and simultaneously calls for a conference with Senate negotiators to iron out the (significant) differences between the two chambers' plans.
"We will have a motion to reject the Senate amendment and go to conference," House Majority Leader Eric Cantor told reporters at a Monday press briefing. "We expect the minority to have a motion to instruct conferees. And then we will have a majority resolution that will lay out our House position that is consistent with the bill that we passed last week."
In other words, House GOP members will get to vote "yes," but in a way that says "no" to the Senate bill. This bears some resemblance to the health care reform-era controversy over so-called self-executing rules, when Democrats briefly considered tying two votes together into one, thus "deeming" unpopular legislation passed. Under the GOP's plan, there's no way for a vote to result in passage of the Senate bill.
Despite the delays and the procedural hijinx, House GOP aides confidently predicted that their measure will pass Tuesday. That would leave Reid to decide whether to stick to his guns or to appoint negotiators to work through the holidays on a full-year plan to renew the payroll tax cut, extend unemployment benefits, and patch a Medicare reimbursement formula to make sure physicians don't take a big paycut on the first of the year. Reid has insisted he considers the matter closed and will leave Boehner holding the ball -- giving him a choice between quelling the rebellion and passing the bipartisan Senate bill before January 1 or triggering a tax increase on middle class workers in a weak economy.
Republicans will hit back and call on Democrats to return to Washington to strike yet another compromise. Complicating that message for them? Many Republicans plan to leave town tomorrow after the close of votes.