Standard & Poor’s made its judgment about both the political standoff and the all-cuts, no-new-revenues deal on Friday when it lowered the country’s long-term debt rating one notch, down from AAA. And while “no new taxes” pledges are almost always big political winners, Americans are also figuring out that the country cannot keep on this way. According to the latest New York Times/CBS News Poll, 63 percent support raising taxes on households that earn more than $250,000 a year to help address the deficit.

If that is not enough to energize the White House, here are a few more facts. To avoid across-the-board cuts, Congress must enact at least another $1.2 trillion in deficit reduction measures over the 10 years. For all of the talk of “big government,” there is no way to cut that much in discretionary programs without crippling basic functions. Lawmakers could eliminate the Federal Bureau of Investigation, Pell Grants, the Centers for Disease Control and Prevention, the National Institutes of Health and Head Start and still not cut $110 billion annually.

Entitlement reform is essential. But it is unlikely that lawmakers will agree on deep cuts to Medicare, Medicaid and Social Security. Finally, asserting that deficits can be tamed with spending cuts alone ignores that the Bush tax cuts — costing $1.8 trillion from 2002 to 2009 — are a big reason we got into this deep hole.

Here is the bottom line. There is no economically sensible or politically honest way to address the deficit without also increasing revenues and reforming the tax code. The major challenges are these:

LET THE BUSH CUTS EXPIRE Mr. Obama vowed to let the high-end tax cuts (for people making more than $250,00) expire in 2010. But in a preview of the debt fight, he agreed to extend the cuts for two more years when Republicans held unemployment benefits and other measures hostage.

Letting all of the cuts expire at the end of 2012 would save $3.8 trillion over the next decade. Letting the tax cuts expire for those making more than $250,000 would save $700 billion. That would make a real dent in the $2.4 trillion in total deficit reduction envisioned in the debt limit deal.