As the leading Keynesian crank, Paul Krugman, recognizes:
Speaking in Michigan, Mr. Romney was asked about deficit reduction, and he absent-mindedly said something completely reasonable: “If you just cut, if all you’re thinking about doing is cutting spending, as you cut spending you’ll slow down the economy.” A-ha. So he believes that cutting government spending hurts growth, other things equal.
Of course, government spending is always an economic and moral negative, whether its source is theft through taxation, theft through inflation, or borrowing, which is ultimately the first or second. (Thanks to M.F. Sands)