I'm cautious about the conventional wisdom that the Democratic Party is about to get flattened by a Republican steamroller. Pollsters are less certain than they'd like you to believe about who's a "likely voter" and who isn't. It's easy to imagine how Democrats, facing near-unanimous predictions of a wipeout, could bestir themselves to narrow the enthusiasm gap by just enough to turn a potential "wave" election into a regular midterm setback for the party in power.

Then again, Democrats might react to the prospect of big losses by pulling the blanket over their heads and going back to sleep. If this happens, Republicans could plausibly win not just the House but the Senate as well. America will have sent Washington a message -- and Washington will go on, basically, with business as usual.

The conservatives and Tea Party activists who believe they're going to fundamentally change the relationship between citizens and their government will become just as disillusioned as the progressives and independents who believed they were fundamentally changing that relationship in 2008. Two years from now, we might well be looking at yet another wave -- surging in the opposite direction. Our politics have become tidal.

Begin with the central argument that Republicans, and especially the Tea Party people, have been making: that the federal government, especially under President Obama, is grotesquely large and tyrannically intrusive.

If the GOP takes control of one or both houses of Congress, voters will expect action to cut the federal beast down to size. All right, the 2010 budget was about $3.5 trillion. Where should the dragon-slayers begin to make meaningful cuts?

If you add up all the items generally thought of as mandatory -- Social Security, Medicare, Medicaid, unemployment benefits, interest on the national debt -- you've already spent about two-thirds of the total. Add in the close to $700 billion spent for defense, which Republicans hold as sacrosanct, and you've spent four-fifths of the budget. This leaves just one-fifth for "discretionary" programs, many of which aren't discretionary at all. I doubt many Americans would want to risk going without food inspection, say, or air traffic control, or the FBI.

It's true, though, that we can't continue to run huge deficits -- for 2010, an estimated $1.3 trillion, according to the Congressional Budget Office. There are two ways to close the gap. One of them, raising taxes, is anathema to today's GOP and has been ruled out by party leaders. The other, slashing expenditures, would mean taking an axe to entitlements. Republicans, looking ahead to the 2012 presidential campaign, aren't going to do anything but pretend to nip at the edges.

Okay, if the revolutionaries of the right aren't likely to make a serious attempt to get the federal budget under control -- and, really, anyone who refuses even to discuss raising taxes isn't serious -- then at least they can reverse some of what Obama has done, right? No, not really.

The president will still have veto power, which makes the whole "undo Obama" thing moot. But set this aside for a moment. Look at the president's most controversial accomplishment, health-care reform. Republicans vow to repeal it. But in their "Pledge to America" manifesto, they promise to replace the system they call "Obamacare" with . . . elements of "Obamacare" that the GOP seeks to rebrand. For example, Republicans say they want to prohibit insurance companies from denying coverage due to preexisting conditions -- just as the president's reform package already does. But they want to do this without a mandate compelling Americans to buy health insurance, and without that mandate the figures don't add up.

All of this is posturing, not policy. Here's the real question: Would Republicans in charge of one or both houses of Congress work with the Obama administration or simply obstruct it at every turn? If they choose the former, true believers will accuse them of aiding and abetting the enemy. If the latter, they open themselves to charges of playing politics at a time when the nation can ill afford such foolishness.

I expect obstruction. That would be bad for the country, but it would be a gift to a White House seeking to regain its political footing. Every time Obama reached out to Capitol Hill and had his hand slapped away, more independents -- frustrated with partisanship and inaction -- would drift back into his column. He'd be well positioned for 2012.

That's the thing about electoral waves: They crash on the perilous shores of reality.

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