After Brenda McClary’s multiple sclerosis began flaring up every few months, she lost her job as a hospital billing clerk, and with it her health insurance.

Since then, the 57-year-old Darby resident has found basic coverage for $127 a month. But the insurance covers just four doctor visits a year, which she has already used up. “Everything from here on out I have to take out of my own pocket,” says McClary, who also has diabetes and has cut back on buying test strips for her blood sugar.

McClary is one of millions of people who might be eligible for a controversial proposal allowing those between 55 and 64 to buy coverage in Medicare, the federal health program for the elderly, before turning 65. The plan, part of a blueprint for health reform written by Max Baucus (D., Mont.), chairman of the Senate Finance Committee, would help people like McClary, who buy their own insurance or are uninsured.

About four million people between 55 and 64 have no health coverage, according to the Census Bureau. Opening up Medicare could be “a way to get some relief to this population immediately,” said John Rother, policy director for AARP, the older-Americans lobbying group.

The proposal might be bolstered by the grinding recession, which is taking a toll on older workers. “These people are getting laid off in the crunch. They can’t find jobs, and they can’t find insurance,” says Robert Laszewski, president of Health Policy & Strategy Associates, a consulting firm in Alexandria, Va. “And they vote.”

Under the Baucus plan, the Medicare expansion would end once a comprehensive health-care overhaul – one that guaranteed insurance to all Americans – was in place.

But the buy-in idea is far from a sure thing. Many Republicans and others oppose the idea, noting that Medicare already faces severe financial problems.

Rep. Tom Coburn (R., Okla.) “believes it would be reckless and irresponsible to add more people to a system that is broken and failing,” says Coburn’s spokesman John Hart.

Politically, the idea stands more of a chance as a temporary transition measure, as Baucus proposes, than as a permanent option if broader health reform fails, says Len Nichols, an economist with the centrist New America Foundation.

But even a temporary measure is likely to face some opposition because “it’s unrealistic to put something like that out there and expect it to ever go away,” says Leslie Norwalk, who was acting administrator of the Centers for Medicare and Medicaid Services under the Bush administration.

Employers would like the option of having their 55- to 64-year-old workers go into Medicare to reduce their own costs, says Norwalk, now a strategic counsel at the law firm Epstein, Becker & Green, in Washington. But allowing a Medicare buy-in could increase costs to the program and its current enrollees, especially if only people in poor health signed up.

“Without a doubt, the political feasibility relates a whole lot to how much this would cost,” says Norwalk.

Then there’s the tricky question of subsidies. Medicare is heavily subsidized for people 65 and older. But to keep this from worsening Medicare’s fiscal woes, the Baucus proposal wouldn’t provide subsidies. The result would likely be far higher premiums than what those over 65 now pay. While the Baucus plan doesn’t give premium estimates, a similar proposal analyzed by the Congressional Budget Office estimated that premiums would be $7,600 a year for those ages 62 to 64.

With such premiums, Medicare’s expenses would not rise, the CBO said, but the government would see a $1.6 billion increase in Social Security payments from 2010-2019 as some people retired early.

If premiums are $7,600 a year, “I can’t see any benefit,” said Jim Cade, 61, who runs a small auto-body shop in Philadelphia. He dropped his insurance three years ago after his monthly premiums rose above $600. “I pray every day I don’t get sick,” he said.

Getting insurance after 50 has never been easy, which is one reason Medicare was created in the first place. “Age is a close proxy for health status,” says Karen Pollitz, research professor at Georgetown’s Health Policy Institute. “While there are a lot of marathon runners in their 60s, it’s also true that the incidence of diabetes, heart disease, and cancer increases after age 50.”

In most states, such as Pennsylvania, insurers can reject applicants for individual coverage if they have medical problems. A survey in 2006 and 2007 by America’s Health Insurance Plans, an industry group, found that 17 percent to 29 percent of all applicants age 50 to 64 were rejected for coverage in the individual market, compared with 10 percent of those age 30 to 34.

Premiums also rise with age. The survey showed that average annual premiums were $3,628 for those age 50 to 54; $4,317 for those 55 to 59; and $5,090 for 60 to 64. The premiums were $1,877 for those 30 to 34.

Robert Zirkelbach, a spokesman for America’s Health Insurance Plans, said that the industry opposed a Medicare buy-in and that there were better ways to help people: The industry has promised to stop rejecting applicants with medical problems and to stop basing rates on health conditions – if a comprehensive health overhaul required everyone to buy insurance.

Baucus also has proposed other ways to help people too young for Medicare. For example, he wants to get rid of a requirement that disabled people under 65 are eligible for Medicare only after a two-year waiting period.

Marlene Chait, 62, a paraplegic who lives in Philadelphia, went through the two-year waiting period and is now on Medicare, but chafing at its restrictions. Because she isn’t housebound – she uses a wheelchair and special van – she isn’t eligible for in-home care and must pay for an aide to help her dress, bathe, and do laundry.

Opening Medicare to younger people is a good idea, and its coverage is “better than nothing,” says Chait. But she says Congress should also expand Medicare to cover more in-home care, so “people like me don’t go bankrupt or lose their house.”