The speed and certainty with which the conventional wisdom in Washington flips can be a comical thing to watch. A mere forty-eight hours ago, Barack Obama was a struggling president, even a likely one-termer. Today, in the wake of the House’s narrow passage of the health-reform bill—which is to say, on the strength of a grand total of four votes, which if cast the other way would have ensured reform’s defeat—he’s suddenly once again a political mastermind and one of the most consequential presidents of the last half-century!

I don’t mean to minimize the importance of the passage of health reform. It is certainly historic—the largest piece of progressive domestic legislation to become law in an astounding 45 years (since Medicare). Obama did place an immense amount of political capital at risk in recent days, speaking personally with more than 90 Democratic House members and rallying them Saturday with a fine and even brave speech in which he called on them to set electoral calculations to the side and do the right thing. Nancy Pelosi, a target of Republican jibes for so many years chiefly because she happens to be from San Francisco, proved herself a skillful leader who is clearly respected across the breadth of her caucus. Against the combined forces of Tea Party rage and hundreds of corporate millions invested in killing the bill, securing its passage was a formidable accomplishment.

But just as liberal despair in recent months was short-sighted and overwrought, the liberal euphoria of today is similarly worth examining, for three reasons.

First, the passage of the bill into law marks a beginning rather than an end. The law’s most conspicuous elements—the creation of the exchanges, the subsidies for coverage, the full range of new regulations governing insurance companies—won’t take effect until 2014. Even when they take effect, myriad complex questions of implementation will need sorting out. Whether the exchanges really work will depend, for example, on the success of “risk adjustment” policies, so that the plans offered in the exchanges won’t vary too greatly in terms of what they charge and offer consumers. There will be dozens of such questions to be answered by future bureaucrats, and inevitably, there will be misjudgments and unforeseen difficulties. The passage of this bill merely starts a health-care debate that will continue, at varying levels of ferocity, for years.

Second, there is the matter of the political consequences of this bill—and the way it was passed— for other Democratic initiatives. It is natural to think that a crucial legislative victory will embolden the winners to push ever onward, aiming their mighty sword at fresh targets. Progressives will certainly hope that this will be the case—with regard to, say, financial reform, or climate change legislation, or immigration reform. It seems to me that there are more reasons to think the opposite will be the case. This battle was so epic that legislators, an extremely cautious class by nature, will be loath to step into another fight like it.

Congress may tackle financial reform this year, since the bill has already progressed fairly far through the Senate (the House passed its version last December). But it seems likely that senators will try to avoid any health-care-style donnybrook. Other legislation of consequence will be put on hold until after the mid-term elections, and depending on how they go, the Democrats may not have the numbers necessary to do anything else of importance.

Which leads into my third reason for caution, the Republican Party. The GOP was determined to make health care Obama’s “Waterloo,” as Republican Senator Jim DeMint put it last year. That failed. But the party shows no signs yet of changing its approach. Here is what Mitt Romney—who as governor of Massachusetts signed into a law a health-care bill that is quite similar in spirit and letter to the one Obama is about to sign, and that, despite budget problems, is working out rather well so far—had to say about Sunday night’s vote:

America has just witnessed an unconscionable abuse of power. President Obama has betrayed his oath to the nation—rather than bringing us together, ushering in a new kind of politics, and rising above raw partisanship, he has succumbed to the lowest denominator of incumbent power: justifying the means by extolling the ends. He promised better; we deserved better. He calls his accomplishment “historic”—in this he is correct, although not for the reason he intends. Rather, it is an historic usurpation of the legislative process—he unleashed the nuclear option, enlisted not a single Republican vote in either chamber, bribed reluctant members of his own party, paid-off his union backers, scapegoated insurers, and justified his act with patently fraudulent accounting. What Barack Obama has ushered into the American political landscape is not good for our country; in the words of an ancient maxim, “what starts twisted, ends twisted.” His health-care bill is unhealthy for America. It raises taxes, slashes the more private side of Medicare, installs price controls, and puts a new federal bureaucracy in charge of health care. It will create a new entitlement even as the ones we already have are bankrupt. For these reasons and more, the act should be repealed. That campaign begins today.

The Republicans failed to block health care simply because the Democrats managed to get it through the Senate while they still had their super-majority of 60 votes. They no longer have that majority, and the near-term prospects of getting any Republicans to agree to work toward good-faith negotiation on anything seem remote (with the possible exception of climate change, on which South Carolina’s Lindsey Graham is supposedly committed to a solution; but on that issue, several Democrats, moderates and others from industrial states, are balking).

The broader partisan logjam will continue. This moment is very much worth savoring, but Obama was not the failure of last week’s conventional wisdom, and he is not the invincible conqueror of this week’s. The march remains a long one.