Should Maine expand Medicaid? That is the question lawmakers are being asked again. To protect Maine’s patients and taxpayers, the answer must be no.

Here’s why: Even before the Affordable Care Act passed in 2010, the state of Maine already had expanded Medicaid. We’ve expanded Medicaid to the point where nearly one in four Mainers now looks to government for health care. We also recently just finished off paying the hospitals back from the last Medicaid expansion.

And what about the Mainers now eligible for Medicaid? Are they receiving the quality care they were promised?

Not even close.

We have serious problems with the Medicaid program already in place. Consider these sad facts:

• Thousands of people — truly vulnerable Mainers in need — are languishing on waiting lists because the program simply cannot support everyone who is currently eligible.

• Nursing homes have been forced to accept reimbursement rates that have remained unchanged for nearly 10 years, while energy and food costs have spiked, resulting in closures of nursing homes, particularly in rural Maine. Our elderly deserve better than that.

• Every session, lawmakers are faced with Medicaid funding shortfalls from high utilization, ineffective funding strategies and costly medical care.

In short, we have plenty to do to fix the existing system without making our problems worse. Adding thousands more people to Medicaid — most of whom are non-disabled, working-age adults with no kids — would stretch an already-broken safety net beyond repair.

A report released this month by the Alexander Group, headed by Pennsylvania’s former secretary of public welfare, also looked closely at the impact of another Medicaid expansion in Maine, finding that “the costs associated with expanding eligibility for MaineCare for the able-bodied residents of working age will place at risk existing commitments Maine has to their traditional Medicaid recipients: those who are disabled and those who are elderly.”

Not only does another Medicaid expansion put truly vulnerable patients at risk, it also threatens the financial security of hard-working Maine families.

Supporters argue that yet another Medicaid expansion won’t cost Mainers anything, as the new costs are paid for by Obamacare. This simply isn’t true. History is an important guide here, as what the federal government “gives” it also may take away.

Maine’s budget woes often are driven by federal mandates that grow exponentially as the federal government adds new layers of costly obligations, while simultaneously reducing its financial commitment to our state. It has happened with education, health care, environmental requirements and public safety.

Remember this: A promise from the government, especially in Washington, is only as good as the next election. Are we prepared to bank on a Washington promise today of billions of dollars when we know, from experience, that money won’t be there tomorrow?

It gets worse.

Obamacare promises to reimburse 90 percent of our Medicaid expansion costs. This means the state would kick in one dollar and get nine back — but only for the new Medicaid expansion population. Remember who these new enrollees are: single, able-bodied, working-age adults with no kids. For the individuals who Medicaid originally was meant to protect — children, seniors and the disabled — the state spends one dollar and gets back just three from Washington.

This creates a perverse incentive during tough budget times to “protect” the high-match able-bodied adults with no kids at the expense of the elderly, children and the disabled — the people who need our help most. That’s wrong.

I will oppose Medicaid expansion and instead fight to take care of Maine’s elderly, the patients sitting on waiting lists and our truly needy kids. People in my district want Maine to keep its commitment to the folks who need our help most, not bank on the latest empty promise from Washington.

I like to think that’s the difference between Maine and Washington: We keep our word.

Sen. Michael Thibodeau, R-Winterport, is the Republican leader of the Maine Senate.