Some 48 of the 100 senators urged Republican leaders and the Bush administration on Wednesday to allow all older people more time to sign up for the Medicare drug benefit beyond the May 15 deadline.

"By extending the enrollment deadline and delaying late enrollment penalties, we can make sure that our constituents are not forced to make hasty decisions about their health care," the senators wrote Majority Leader Bill Frist, R-Tenn.

The administration has extended the enrollment period for some low income people. That could affect 2 million people whose incomes are below 150 percent of the poverty level — $14,355 for an older person who lives alone, $19,245 for a couple. Administration officials said last week they lack the legal authority to extend it for everyone.

Sen. Debbie Stabenow, D-Mich., who has written legislation to extend the deadline, acknowledged in a conference call with reporters that the letter does not have enough signatures to make Frist bring the issue up again. A similar measure was narrowly defeated last year.

Signing Stabenow's letter were four Republican senators: Olympia Snowe of Maine, Mike DeWine of Ohio, Lincoln Chafee of Rhode Island and Arlen Specter of Pennsylvania.

Participants in the conference call said as many as 15 million older people who are eligible for the benefit have yet to enroll. There are about 43 million eligible Medicare beneficiaries.