Yesterday The Times published a highly informative chart laying out the positions of the presidential candidates on major issues. It was, I'd argue, a useful reality check for those who believe that the next president can somehow usher in a new era of bipartisan cooperation.
For what the chart made clear was the extent to which Democrats and Republicans live in separate moral and intellectual universes.
On one side, the Democrats are all promising to get out of Iraq and offering strongly progressive policies on taxes, health care and the environment. That's understandable: the public hates the war, and public opinion seems to be running in a progressive direction.
What seems harder to understand is what's happening on the other side - the degree to which almost all the Republicans have chosen to align themselves closely with the unpopular policies of an unpopular president. And I'm not just talking about their continuing enthusiasm for the Iraq war. The G.O.P. candidates are equally supportive of Bush economic policies.
Why would politicians support Bushonomics? After all, the public is very unhappy with the state of the economy, for good reason. The "Bush boom," such as it was, bypassed most Americans - median family income, adjusted for inflation, has stagnated in the Bush years, and so have the real earnings of the typical worker. Meanwhile, insecurity has increased, with a declining fraction of Americans receiving health insurance from their employers.
And things seem likely to get worse as the election approaches. For a few years, the economy was at least creating jobs at a respectable pace - but as the housing slump and the associated credit crunch accelerate and spill over to the rest of the economy, most analysts expect employment to weaken, too.
All in all, it's an economic and political environment in which you'd expect Republican politicians, as a sheer matter of calculation, to look for ways to distance themselves from the current administration's economic policies and record - say, by expressing some concern about rising income gaps and the fraying social safety net.
In fact, however, except for Mike Huckabee - a peculiar case who'll deserve more discussion if he stays in contention - the leading Republican contenders have gone out of their way to assure voters that they will not deviate an inch from the Bush path. Why? Because the G.O.P. is still controlled by a conservative movement that does not tolerate deviations from tax-cutting, free-market, greed-is-good orthodoxy.
To see the extent to which Republican politicians still cower before the power of movement conservatism, consider the sad case of John McCain.
Mr. McCain's lingering reputation as a maverick straight talker comes largely from his opposition to the Bush tax cuts of 2001 and 2003, which he said at the time were too big and too skewed to the rich. Those objections would seem to have even more force now, with America facing the costs of an expensive war - which Mr. McCain fervently supports - and with income inequality reaching new heights.
But Mr. McCain now says that he supports making the Bush tax cuts permanent. Not only that: he's become a convert to crude supply-side economics, claiming that cutting taxes actually increases revenues. That's an assertion even Bush administration officials concede is false.
Oh, and what about his earlier opposition to tax cuts? Mr. McCain now says he opposed the Bush tax cuts only because they weren't offset by spending cuts.
Aside from the logical problem here - if tax cuts increase revenue, why do they need to be offset? - even a cursory look at what Mr. McCain said at the time shows that he's trying to rewrite history: he actually attacked the Bush tax cuts from the left, not the right. But he has clearly decided that it's better to fib about his record than admit that he wasn't always a rock-solid economic conservative.
So what does the conversion of Mr. McCain into an avowed believer in voodoo economics - and the comparable conversions of Mitt Romney and Rudy Giuliani - tell us? That bitter partisanship and political polarization aren't going away anytime soon.
There's a fantasy, widely held inside the Beltway, that men and women of good will from both parties can be brought together to hammer out bipartisan solutions to the nation's problems.
If such a thing were possible, Mr. McCain, Mr. Romney and Mr. Giuliani - a self-proclaimed maverick, the former governor of a liberal state and the former mayor of an equally liberal city - would seem like the kind of men Democrats could deal with. (O.K., maybe not Mr. Giuliani.) In fact, however, it's not possible, not given the nature of today's Republican Party, which has turned men like Mr. McCain and Mr. Romney into hard-line ideologues. On economics, and on much else, there is no common ground between the parties.
Paul Krugman is Professor of Economics at Princeton University and a regular New York Times columnist. His most recent book is The Conscience of a Liberal.
© 2007 The New York Times