Americans have made it clear that they want a certain kind of government, one that can field a strong military and also maintain popular programs like Medicare. Yet we are not paying nearly enough taxes to maintain those programs. Even major changes to the health care system — the single most important step for closing the budget gap — will not close it entirely. Taxes must rise, too.

This is a point on which serious Democrats and serious Republicans agree, even if they do so with euphemism. “We are on an unsustainable path,” says Peter Orszag, Mr. Obama’s budget director. Judd Gregg, the ranking Republican on the Senate Budget Committee, has said, “Revenues are going to have to go up.” Douglas Holtz-Eakin and Dan Crippen, budget experts who advised the McCain campaign, have quietly acknowledged the same.