Washington ? As Tuesday’s starting date approaches for the Medicare drug discount program, the number of older Americans enrolling for the new benefit has been disappointing, according to some card sponsors.

While most of the more than 70 sponsors are silent about how many they’ve signed up, AARP admits its number is minuscule. The group, which has 35 million 50-and-older members, mailed out 26,000 enrolling kits and has signed up only 400 people, spokeswoman Carol Shirley said.

At Walgreen Co., spokesman Michael Polzin said, “We prepared for a crush of seniors to come in beginning in May. That hasn’t happened.”

The Bush administration projected that 7.3 million Medicare recipients would sign up for the cards, which can be used beginning June 1. That number includes 4.7 million with incomes low enough to receive $600 from the federal government this year and again in 2005 to pay pharmacy bills.

If enrollment to date is lower than expected, it can be attributed partly to advice from Health and Human Services Secretary Tommy Thompson and others to window-shop before choosing a card. On Thursday, Thompson said, “Now is the time to sign up.”

AARP’s Shirley said the rollout of the drug card program also had been “a bit rocky.” Problems have included swamped phone lines at the Medicare hot line, which Thompson and others consider evidence of high interest in the program, and discrepancies between prices posted on the Medicare Web site and what the card sponsors say they are charging for some medicines.

Ruth Nadel, a member of the advisory Commission on Aging in Washington, stood up at Thompson’s news conference to complain that the Web site was difficult to use, a point reinforced by analysts at Forrester Research in Cambridge, Mass.

“The site’s flaws make picking the right card a cumbersome task,” Forrester’s Elizabeth Boehm said.

In addition, some advocacy groups and Democratic critics of the new Medicare prescription drug law have challenged the discounts available with the cards. Bush administration officials say brand-name drugs can be had for up to 18 percent less than the retail price, on average. Two reports this week said drug price inflation in recent years exceeded the discounts.