Baucus gives an interview to the NYT and says he'll increase subsidies for low-income families. Times says the changes could add $28 billion to the cost over a decade, or $2.8 billion a year. That doesn't sound like enough to make much of a difference. But if the figure can move once, it can move again. In a bill that also requires people to have health coverage, increasing subsidies for people who can't afford it is the right thing to do. Boosting the assistance for lower-income folks by a material amount will raise the cost of a bill whose chief selling point had been its affordability.

Reality intrudes again. If you're going to cover everybody, it will cost a lot of money. Revenue has to be found to pay for this. It's worth doing. But do it with eyes open.

Mr. Baucus said the changes showed that he had heard the criticism of his bill from colleagues, who asserted that many people would be required to buy insurance who could not afford it — even with federal subsidies to help defray the cost of premiums.

“Affordability — that, I think, is the primary concern,” Mr. Baucus said. “We want to make sure that if Americans have to buy insurance, it’s affordable.”