Compounding the problem, Obama proposed his stimulus shortly after the Congressional Budget Office predicted deficits topping a trillion dollars. Even before Obama took office, and for months afterward, “everybody who mattered” insisted that the crisis required Obama to scale back the domestic initiatives he campaigned on, especially health care reform, but also cap-and-trade, financial regulation and so on. Colin Powell, a reliable barometer of elite opinion, warned in July of 2009: “I think one of the cautions that has to be given to the president — and I’ve talked to some of his people about this — is that you can’t have so many things on the table that you can’t absorb it all. And we can’t pay for it all.”

Rather than deploy every ounce of his leverage to force moderate Republicans, whose votes he needed, to swallow a larger stimulus than they wanted, Obama clearly husbanded some of his political capital. Why? Because in the position of choosing between the agenda he came into office hoping to enact and the short-term imperative of economic rescue, he picked the former. At the time, this was the course liberals wanted and centrists opposed.

On two subsequent occasions, Obama faced this same choice. Last December, he could have refused to extend any of the Bush tax cuts on income over $250,000. Republicans vowed to let all the tax cuts expire if he did so. If Obama let this happen, it would have almost fully solved the long-term deficit problem, while at the same time setting back the recovery by raising taxes on middle-class and low-income workers. Obama decided to make a deal, extending all the Bush tax cuts and also securing a progressive payroll tax cut and an extension of unemployment benefits, both forms of stimulus that Republicans would never have allowed without an extension of upper-bracket tax cuts in return.

There is a decent argument that the president should have refused this deal. But if you make that argument, you have to accept the likelihood that nearly a million fewer jobs would have been created and that we would have been at risk of a double-dip recession back then. Yet the liberal critics most exercised about Obama’s failure to secure more stimulus were, for the most part, enraged when he did exactly that. Take Robert Reich, the former secretary of labor under President Clinton. Last November, Reich pleaded for an extension of unemployment benefits, calling the plight of the jobless our “single newest and biggest social problem.” When Obama made his bargain, Reich called it “an abomination,” complaining that “the bits and pieces the president got in return” — including the unemployment benefits previously deemed vital — amounted to “peanuts.”

And then, this summer, Obama let the G.O.P. hold the debt-ceiling vote hostage to extract spending cuts. I think he should have called the Republicans’ bluff and let them accept the risk of a financial meltdown. But the reason Obama chose to cut a deal is that calling their bluff might have resulted in catastrophe. And Obama made a point of back-loading the G.O.P.’s budget cuts so as not to contract the economy. He may have chosen wrongly, but he chose exactly the priorities liberals now insist he ignored — favoring economic recovery over long-term goals.

Liberal critics of Obama, just like conservative critics of Republican presidents, generally want both maximal partisan conflict and maximal legislative achievement. In the real world, those two things are often at odds. Hence the allure of magical thinking.