BARACK OBAMA must savor the moment while he can. It may never get better than this.

As he stood before Congress on Tuesday night, the new president was armed with new job approval percentages in the 60s. After his speech, the numbers hit the stratosphere: CBS News found that support for his economic plans spiked from 63 percent to 80. Had more viewers hung on for the Republican response from Bobby Jindal, the unintentionally farcical governor of Louisiana, Obama might have aced a near-perfect score.

His address was riveting because it delivered on the vision he had promised a battered populace during the campaign: Government must step in boldly when free markets run amok and when national crises fester unaddressed for decades. For all the echoes of F.D.R.’s first fireside chat, he also evoked his own memorably adult speech on race. Once again he walked us through a lucid step-by-step mini-lecture on “how we arrived” at an impasse that’s threatening America’s ability to move forward.

Obama’s race speech may have saved his campaign. His first Congressional address won’t rescue the economy. But it brings him to a significant early crossroads in his presidency  one full of perils as well as great opportunities. To get the full political picture, look beyond Obama’s popularity in last week’s polls to the two groups of Americans whose approval numbers are in the toilet. There is good news for Obama in these findings, but there’s also a stark indication of the unchecked populist rage that could still overrun his ambitious plans.

The first group in national disfavor is the G.O.P. In the latest New York Times/CBS News survey, 63 percent said that Congressional Republicans opposed the stimulus package mostly for political reasons; only 17 percent felt that the Republicans should stick with their own policies rather than cooperate with Obama and the Democrats. The second group of national villains is corporate recipients of taxpayer money: only 39 percent approve of a further bailout for banks, and only 22 percent want more money going to Detroit’s Big Three.