Democrats, who wrote the legislation and provided most of its votes, generally portray themselves as champions of the poor. They do not dispute that the tax plan would hit poor communities disproportionately, but they say it is worth it to provide health insurance to millions of modest-income children.

All the better, they say, if higher cigarette taxes discourage smoking.

"I'm very happy that we're paying for this," Senate Majority Leader Harry Reid, D-Nev., said in an interview Friday, noting that the plan would not add to the deficit. "The health of the children is extremely important," he said. "In the long run, maybe it'll stop people from smoking."

Congress probably will revisit the cigarette tax issue soon because President Bush has pledged to veto the proposed $35 billion expansion of the State Children's Health Insurance Program. The decade-old program helps families buy medical coverage if their income is too high to qualify for Medicaid.

Bush has proposed a more modest growth for the program, and both political parties seem inclined to pay for it through a tax on an unpopular group, cigarette smokers.

By most measures, the average smoker is less privileged than the average nonsmoker. Nearly one-third of all U.S. adults living in poverty are smokers, compared with 23.5 percent of those above the poverty level, according to government statistics.

The American Heart Association reports that 35 percent of people with no more than 11 years of schooling are smokers. Those with 16 or more years of formal education smoke at a 12 percent rate.

Non-Hispanic black men smoke at slightly higher rates than do non-Hispanic white men. But the reverse is true among women.

The demographics of smoking and taxation received scant attention during last week's House and Senate debates, perhaps because many Democrats and Republicans agree that cigarettes are the best target for tax increase if the insurance program were to grow. A few lawmakers, however, took a swing.

"I know there is very little sympathy for smokers these days," Rep. Jack Kingston, R-Ga., said during the House debate. "But it is still a tax increase on the backs of the smokers. And in order to get enough money to pay for this, it would require 22 million new smokers."

Rep. Frank Pallone, D-N.J., defended putting the burden of expanded medical care on smokers.

"The tobacco tax is a great way to pay for it," he said, "because if you tax people who are smoking and they smoke less, then we have less health problems."

Rep. Jim McCrery, R-La., did not buy that logic. "To propose funding a growing program with a declining revenue source is, I would submit, irresponsible fiscal policy," he said.

If the federal cigarette tax nears $1 per pack, smokers in many states will pay hefty sums into government coffers unless they kick their habit. On top of the federal tax, New Jersey levies a $2.57 per pack tax on cigarettes, followed by Rhode Island at $2.46.

California is near the middle, at 87 cents a pack. Three states tax cigarettes at less than 30 cents per pack. South Carolina is the lowest at 7 cents.

Bill Phelps, spokesman for Philip Morris USA, based in Richmond, Va., said a steep federal tax increase could accelerate the national decline in smoking to the point that the insurance would have to find other revenue sources.

The average U.S. price of a pack of cigarettes has risen by 80 cents since 1999, Phelps said, largely because of state tax increases. State and federal governments received more than $21 billion in cigarette excise taxes in the 2006 budget year, he said, "so we think this trend is unfair to adults who smoke and to retailers who sell tobacco products."

In Congress, these groups receive little sympathy. But some lawmakers say voters should know the details of the insurance program's proposed funding structure.

Rep. Mike Pence, R-Ind., who spoke against the bill in last week's debate, said: "The headline ought to read, 'Smokers in America to pay for middle-class welfare.'"