WASHINGTON - President Clinton is to propose this week lowering to 62 the age of Americans eligible for Medicare benefits, an administration official said Saturday.The proposal, which if implemented would mark the first time Medicare is made available to those under 65, will be part of Clinton's proposed spending plan for the fiscal year beginning Oct. 1.It is one of several spending initiatives the president plans to propose in the new budget, said the official, speaking on condition he not to be identified. Other proposals would restore food stamp benefits to some legal immigrants and focus on biomedical research.The official said Clinton would continue to limit federal spending and avoid expensive initiatives that would explode the budget. Since raising taxes on wealthy Americans and cutting federal spending in 1993, the president has seen the federal deficit steadily shrink each year."It is possible, in the context of moving towards that balanced budget, to begin to expand a little bit on some of the spending programs that are available for people who really have real needs," White House spokesman Mike McCurry said Saturday on CNN's "Evans and Novak."As more companies refuse to provide health coverage to retirees, many people find themselves unable to afford insurance until Medicare eligibility begins at age 65."This is a problem that needs to be addressed," said Andrea Hofelich, spokeswoman for Rep. Nancy L. Johnson, R-Conn., a senior member of the House Ways and Means Committee's health subcommittee.While the administration official would not discuss details of Clinton's plan until the president presents it this week, both The Washington Post and The Wall Street Journal reported it would allow people between 62 and 64 to pay up to $400 a month for health coverage.Administration officials also are looking at ways for Medicare to cover Americans aged 55 to 61, but officials say that may prove unaffordable. The over-55 group is second only to children in the percentage of Americans lacking health insurance.The food stamp proposal is the latest effort to restore some of the benefits taken from legal immigrants in the 1996 law overhauling welfare. Even when he signed the bill into law, Clinton said he disagreed with some of its provisions and would work to amend them.Last year, the president and Congress agreed to restore disability and Medicaid benefits to legal immigrants and included that provision in the balanced budget agreement. During negotiations, the sides could not agree on including food stamps. Hence, the president plans to try again in his budget proposal, though details are not complete.Another area of the budget drawing interest from Clinton is biomedical research. He has been a long-standing supporter of allocating federal funds for such research. In his new budget, he plans to push for a $1 billion increase in funding for biomedical research at the National Institutes of Health, The New York Times reported. In addition, the newspaper, said, some lawmakers may try to double the institutes' budget, now at $13.6 billion this year, over the next five years.