Washington ? “No good deed goes unpunished.” That ironic aphorism has become the opening line for Bill Novelli, the embattled chief executive of AARP, the 35 million-member behemoth of Washington interest groups.

Many Democrats would bitterly dispute whether it was “a good deed” when Novelli swung the giant senior citizens organization, formerly known as the American Association of Retired Persons, behind the Bush administration’s Medicare reform/prescription drug bill, just before the critical House vote on the measure last autumn.

What is not in dispute is that the decision to back the bill providing the first drug benefit to Medicare patients and expanding the role of private insurers in the government’s popular health care system for seniors has provoked the greatest crisis in the recent history of AARP.

While overall membership has continued to grow, Novelli says 60,000 members canceled or refused to renew in protest of the organization’s backing.

When I asked in an interview on Tuesday if he thought that most of the controversy was behind him, Novelli said, “No way.”

“It’s a mess,” he said. “You’ve got people investigating a congressman’s complaint that his arm was broken” during the unprecedented three-hour, predawn roll call, when a Cabinet official and Republican House leaders were pressuring members for the votes to reverse an apparent defeat of the measure. He was referring to the complaint from retiring Rep. Nick Smith of Michigan that he was told his vote would influence whether his son, now running for Smith’s seat, would get financial help in his race.

“Then the cost estimate turns out to be wrong” — a little matter of the bill’s 10-year toll jumping from $400 billion to $535 billion. And just last week, the civil servant who is Medicare’s chief actuary charged that the political appointee who ran the program threatened to fire him if he made the true cost known to members of the House before the vote. That, too, is now under investigation.

“This is more than a spectacle,” Novelli said. “It’s an embarrassment.” And it makes it very hard for AARP to do the job of selling its members — and other seniors — on the notion that this bill will be good for them and is not the disaster that Democratic nominee John Kerry and others claim.

Kerry and most of his fellow Democrats, along with organized labor and other liberal interest groups, assert that the drug benefit is too skimpy to be meaningful and that the changes in Medicare’s structure will lead to its downfall as a universal benefit.

Novelli said that the polling AARP has done suggests that almost three out of four seniors either are unaware of the basics of the bill Bush signed into law or are so confused by what they have heard that they can’t express an opinion.

But among the quarter of the beneficiaries with an opinion, “the majority are opposed,” Novelli said. That is not a comfortable position for the organization that purports to speak for them.

So AARP is out advertising and promoting the product. The latest effort is a TV spot using humor to acknowledge that this is one complicated puzzle to understand and suggesting that viewers can get help from an AARP brochure.

The prescription drug benefit is scheduled to come into Medicare starting in 2006, but the first practical test of the new legislation will occur this summer, when seniors are eligible to receive drug discount cards that supposedly will save them 10 percent to 35 percent on their bills.

Novelli said AARP is part of a coalition of 20 national organizations that will mount a drive to encourage seniors, particularly those with low incomes, to apply for the discount cards.

But he is plainly worried about how his constituents will cope with the plethora of competing plans that are out there — and how complicated the government will make the application process.

Whatever critics may say about AARP’s many commercial enterprises in marketing insurance and other products to seniors, the ethic of the organization remains one of a social service agency. It has a lot riding on what happens when seniors actually reach for the benefits this bill is supposed to provide.

To say that its credibility — and that of the Bush administration — is at stake is an understatement.

David Broder is a columnist for Washington Post Writers Group.