The politics of the GOP's en masse opposition to the stimulus bill aren't complicated.
There's a reasonable chance that the stimulus won't be sufficient, or will become bogged down in the inefficiency and waste of easily boogiemanned Big Government Badness. If the economy hasn't kicked into a forward gear 18 months from now, this vote could be leveraged to create a sea change in the House.
The GOP wants Obama and his Democratic compatriots to own this package. And understandably so. In its particulars the stimulus is a rejection of the last 8 years of doing business. If it works, it's a validation of Democratic rule, and the GOP won't win any brownie points for having hitched its caboose to this train.
Many liberals are now peeved that Obama wasted so much time and sacrificed "so much" to offer the GOP an hand in partnership only to receive this all too familiar slap in the face. But let's understand something -- Obama didn't sacrifice. It's clear that Larry Summers & Co. actually believe in tax cuts as stimulus. The size of the tax cut package here was going to make many progressives gasp. So Obama leaked it to the Wall Street Journal and framed it as a necessary measure to shore up bi-partisan support. He's playing the angles to make it appear he was corralled into the centrist position he actually started from.
The optics here all work in Obama's favor. Assuming the Senate doesn't now drop the ball, he'll get a massive stimulus package that delivers Big Time on his campaign promises without the burden of, you know, actually coming up with revenues to pay for middle class tax cuts and rebates, digitized health records, expanded Pell grants, a smart grid, rural broadband, energy efficiency programs, etc. etc.
And the kabuki theater of attempting to meet the GOP half way has the effect of conserving political capital. Obama is getting everything he really wants out of this package without having to ram it down anyone's throat. He's looking reasonable and post-partisan -- as true to his brand as the petulant and ideological House GOP appears to its own.