With the House and Senate meeting this week to sort out differences over the $400 billion expansion of Medicare, Maine’s congressional delegation should be clear about what it expects from the legislation and what is unacceptable. Clearly, the Senate has assembled a package that better protects seniors in rural areas, but just as clearly the majority of the members of Congress who will negotiate an agreement on the prescription-drug bill could lean toward the barely passed House version.

The conference between houses to reconcile their bills is likely to focus on how far Congress will go to encourage private plans to compete with traditional Medicare, a competition the House, but not the Senate, would begin in 2010. It will debate whether the government would provide equal prescription drug coverage if private plans lacked competitors – in the Senate bill but not the House version. And only the House includes the option of medical-savings accounts that are estimated to cost the federal government $174 billion over 10 years and may save money for individuals but would result is lesser benefits in the drug plans.

Also to be decided is how and whether Medicaid would offer coverage to the 6 million low-income seniors who are eligible for both it and Medicare – the Senate, but not the House, would require states to continue Medicaid coverage. And there are questions of deductibles and co-payments and issues specific to rural areas such as reimbursement rates for care providers.

Sen. Olympia Snowe, who spent years working on a Medicare prescription drug plan and who is a member of the Senate Finance Committee, could have expected to be named to the conference, adding a moderate voice to what is a conservative group. Instead, she was passed over by Senate Majority Leader Bill Frist, who instead chose the more conservative Sen. Jon Kyl of Arizona. Dr. Frist also appointed himself to the conference, suggesting the importance of the legislation.

Sen. Snowe and other members of Congress are preparing a list of what they will support and what will cause them to vote against the measure. They should make the protection of the health care program their priority. Sen. Susan Collins said the standard for an acceptable Medicare bill is that it “provide rural Mainers with the same benefits that would be available to seniors who live in urban communities.” Sen. Collins said that her priorities are to ensure the drug benefit provides substantial coverage for low-income seniors, ensure health care payments to rural hospitals and health care agencies are increased and maintain a provision she authored that removes barriers to generic drugs entering the market.

Some Republicans hesitant about the drug expansion are correct to observe that Medicare will become unsustainable under its current system and rate of growth, but the answer is far more complicated than hoping a profit-driven private system finds answers. Medicare must be examined as part of a much more comprehensive system, one that offers coverage to many more healthier people, spreading risk over a larger pool, that insists on tough negotiations with the pharmaceutical industry and changes patient expectations, from an early date, about the responsibilities they have for their own health.

This is an enormous challenge that will grow more complicated as more seniors depend on Medicare benefits and the amount of time left to avert a bankruptcy in the system becomes shorter. Medicare should have included a drug benefit years ago; under the right circumstances, it could have one in the next few years. After the drug benefit is passed, even harder work remains.