From my USA Today column:

Are Republicans hypocrites for caring about the deficit? Maybe. But that’s OK.
The tricky thing about cries of hypocrisy in a two-party system is that the accusation almost always cuts both ways. The Democrats say “cats are the best!” and the Republicans say “dogs rule!” A couple of elections later, the Democrats suddenly discover they need dogs more than cats and switch positions. Republicans immediately whine about Democratic hypocrisy, even as they meet with important members of the feline community to say, “See, the Democrats are abandoning you. We have room for cats in the GOP’s big tent.” This in turn causes Democrats to vent their spleens about the GOP’s own hypocrisy, reminding voters of the Republican Party’s long history of indifference to the litter-box-using community.
The same dynamic can be found in debates about any number of issues, from race relations and foreign policy to trade and Supreme Court appointments. The parties, and their partisans, switch sides like boys and girls at a square dance and then shout “hypocrite!” at each other from either side of the political barn.
Perhaps nowhere is that more true than the typically soporific issue of budget deficits. For decades, Republicans were the budget hawks, green eyeshades firmly in place, deploring the profligate habits of liberal Democrats who cared too little about deficit spending. Then, as the Reagan deficits ballooned (with the aid of a fiscally promiscuous Democratic Congress) the right started caring less about deficit spending, while the left suddenly saw an opportunity to rehabilitate its image as bleeding-heart hippies spending somebody else’s money.