JEFFERSON CITY, Mo. -- For a dozen years, Missouri has offered low-income senior citizens some type of aid to pay for their prescription drugs. But that may be about to end.

The Missouri Rx Plan, which helps pay the medicine costs of 212,000 seniors and disabled residents, is due to expire Aug. 28 unless lawmakers renew it. So far, they have not done so. And a Senate budget plan is banking on its demise, redirecting millions of dollars that normally would fund the prescription program to other government purposes.

Gov. Jay Nixon's administration is urging lawmakers not to let the program lapse.

"For the health and safety of our senior citizens and Missourians with disabilities, it is imperative that this program is reauthorized," said Ron Levy, director of the Department of Social Services, which oversees Missouri Rx.

Missouri lawmakers have until May 6 to pass a budget. They have until May 13 to pass a bill reauthorizing the program's existence.

The current Missouri Rx Plan is the state's third attempt at helping seniors pay for their medicine. But some lawmakers wonder if the need for such aid is diminishing because of a new federal health care law that reduces out-of-pocket prescription costs for people covered by Medicare.

Nixon, a Democrat, held a news conference in December urging lawmakers to renew Missouri Rx for an additional five years. Republican House Speaker Steven Tilley, of Perryville, has cosponsored legislation to do so.

The program extension received initial House approval this past week as part of a broader health care bill. The House Budget Committee this past week also tacked the Missouri Rx extension onto a previously passed Senate bill.

But the House committee action came on the same day the Senate passed a budget without any money for Missouri Rx.

Senate Appropriations Committee Chairman Kurt Schaefer, R-Columbia, said the money was stripped because the program is due to expire, "and I don't see anything on the immediate horizon showing it's going to be renewed."

Schaefer declined to say whether he personally supports the renewal of Missouri Rx. But he noted Missouri already spends a lot on prescription drugs, including $972 million of federal and state funds for Medicaid patients in the proposed 2012 budget and $187 million in state repayments to the federal government for Medicare prescription benefits.

Also, because of the changes in the federal health care law, "much of the need has gone away," Schaefer said.

Starting this year and continuing through 2020, the federal Medicare program is gradually closing its coverage gap by paying a greater share of people's prescription costs.

But the state Department of Social Services says that doesn't alleviate the need for Missouri Rx, because most of its subsidies for prescription drugs are paid on behalf of Missouri residents who haven't yet racked up enough bills to enter the so-called "doughnut hole."

Sen. Jason Crowell, R-Cape Girardeau, said he believes lawmakers ultimately will bow to political pressure and agree to renew the program. But he fears that restoring Missouri Rx to the budget will come at the expense of education, particularly a $20 million boost the Senate had approved in school busing aid.

"We're in fantasy la-la land if we honestly think we're not going to renew the Senior Rx program," Crowell said.