Republicans don't oppose stimulus when it fits their policy agenda
It's worth recalling that Republicans didn't always mistrust stimulus. They didn't even mistrust deficit-financed stimulus (not that there are many other kinds). Back when they were selling the Bush tax cuts, the original argument was that the economy was great and the government was running a surplus and you should get your money back. But then the economy tanked when the tech bubble burst. No problem! “Because the economy is slowing down, I believe it is vital that Congress pass a pro-growth tax cut," said Dick Armey. We're all Keynesians when convenient.
Tax cuts tilted toward the rich do stimulate the economy, of course. But they don't do it very well. According to Mark Zandi's numbers (pdf), you get 32 cents of stimulus per dollar spent on the Bush tax cuts. That's because tax cuts that tilt towards the rich boost how much money they save, not how much they spend. Compare that with state and local aid, which give you a $1.41 of stimulus for each dollar spent.
By Ezra Klein
June 18, 2010; 5:00 PM ET
http://voices.washingtonpost.com/ezra-klein/2010/06/republicans_dont_oppose_stimul.html