HARTFORD, Conn. – Senior citizens in New England face a broad – and potentially confusing – array of choices among prescription drug plans that were announced Friday.

The Bush administration on Friday named 10 insurers to provide a prescription drug program to an estimated 30 million senior citizens nationwide as part of the largest expansion in Medicare ever.

However, insurers also submitted bids for regional contracts, driving up the number of companies approved by the federal Centers for Medicare & Medicaid Services.

Senior citizens in Connecticut, Massachusetts, Rhode Island and Vermont can choose from 17 stand-alone prescription drug plans. In Maine and New Hampshire, seniors have 16 choices.

Enrollment begins Nov. 15 for the prescription drug plan, which starts Jan. 1.

The number of Medicare beneficiaries ranges from nearly 1 million in Massachusetts to 97,954 in Vermont, according to the Centers for Medicare & Medicaid Services.

Rather than choosing from a single Medicare drug plan, seniors will be allowed to select from numerous programs offered by the insurance companies. Insurers will begin marketing their offerings Oct. 1, and cannot release details about their plans until then.

Many insurers hope to win over seniors by emphasizing simplicity and ease in understanding complicated prescription plans.

“Our entire premise is simplifying this,” said Marian Cutler, spokeswoman for HealthNet in Shelton. “We’ve taken away claim forms and paperwork. We make it easy, easy, easy.”

Tricia Neuman, vice president of the Kaiser Family Foundation, a health policy organization, said the process of participating in the drug program may not be what’s complicated.

“Locally, if you’re in an area with a stand-alone drug program and HMOs and PPOs, the confusion is understanding the difference in the products,” she said.

The choices are even greater because beneficiaries also may get drug coverage through Medicare Advantage Plans, which operate like health maintenance organizations and offer more comprehensive coverage than just a drug benefit.

But no Medicare Advantage Plan operates in Vermont, leaving seniors with fewer choices.

Charlotte Yeh, the Boston regional administrator for the Centers for Medicare & Medicaid Services, said the absence is due to Vermont’s character.

“It’s very rural. Historically, it never had managed plans,” she said.

It could eventually be filled by regional preferred provider organizations, said Yeh, a physician.

Seniors in Connecticut can choose from four Medicare Advantage Plans. Maine and New Hampshire each have one Medicare Advantage Plan, Massachusetts has six and Rhode Island has two.

Vermont state Sen. James Leddy, chairman of the Senate Health and Welfare Committee, said Vermont has several plans that are “effectively HMOs.”

“The fact you have an HMO does not mean things are working as you might want them,” said Leddy, D-South Burlington. “Health care costs in Vermont are among the lowest in New England.”

Jason Gibbs, spokesman for Vermont Republican Gov. Jim Douglas, would not comment on the federal prescription drug program. Vermont is served by only three health insurance companies, which “centers around a lack of options,” he said.

“A great many Vermonters want to find more affordable options in the marketplace,” he said.