Paul Krugman argues this morning that Mitt Romney probably doesn’t believe the various Republican economic myths he’s been campaigning on, but that:

For the cynicism and lack of moral courage that have been so evident in the campaign wouldn’t suddenly vanish once Mr. Romney entered the Oval Office. If he doesn’t dare disagree with economic nonsense now, why imagine that he would become willing to challenge that nonsense later? And bear in mind that if elected, he would be watched like a hawk for signs of apostasy by the very people he’s trying so desperately to appease right now.

I think Krugman's general case is correct: Whatever his “real” beliefs about public policy issues, Romney would no doubt stick close to the mainstream conservative line on most things if he were in the Oval Office. The research is pretty clear that presidents try to keep their campaign promises. Beyond that, this is an era of a partisan presidency, and that means that Romney would be surrounded in the White House by mainstream conservatives who probably really would believe in the promises Romney has made.

However, on the particular question Krugman is talking about — whether Romney will follow conventional Keynesian policies once in office — I think it’s a little more complicated. Republicans do have some core economic principles, such as a belief that tax cuts are always a good thing. But a lot of the anti-Keynesian talk we’ve heard over the past three years is almost certainly partisan, and not ideological, in nature. George W. Bush didn’t react to either recession during his time in office by championing spending cuts, after all. Indeed, the partisan impulse to oppose anything Barack Obama supports is so strong that Republicans generally opposed Obama’s payroll tax cut and can’t manage to acknowledge the existence of tax cuts in Obama’s stimulus back in 2009, much less support them.

No, the truth is that a President Romney probably would completely forget about the argument that austerity is the best medicine for an ailing economy. His mix of policies would presumably be heavier on tax cuts than on spending, and those tax cuts would be balanced differently than Barack Obama’s would be. But I’d be very surprised if Republicans really do press austerity if they win unified control of government.