Updated

The Senate blocked legislation on Wednesday that would let the government negotiate Medicaredrug prices. Democrats couldn't muster the 60 votes needed to bring the bill up for a vote.

Under the Medicare drug benefit, private insurance plans negotiate with drug makers over the price of medicine for their customers. About 22 million seniors and the disabled are enrolled in such plans. Some lawmakers, mostly Democrats, contend the government could use its leverage to drive a better bargain than individual insurers, which would lower the cost of the program for taxpayers and seniors.

But Republicans countered Wednesday that the program is costing much less than expected precisely because it's the private sector, not the secretary of Health and Human Services, conducting the negotiations. They successfully blocked a motion to proceed to the bill. The tally was 55-42, five short of the votes needed to move ahead.

Sen. Mitch McConnell, R-Ky., said the program will cost about $265 billion less than anticipated over the coming decade.

"I doubt a single government program in modern history, let alone one this big and this important has ever, ever come in under budget," McConnell said. "So it's a mystery why our Democratic friends would want to tamper with this Medicare drug benefit. If it isn't broke, why fix it?"

Democratic lawmakers countered that they weren't aiming for a government takeover of the drug benefit, only to let the secretary of Health and Human Servicesintervene for particular kinds of expensive drugs that have no substitute, such as some of the drugs taken by cancer patients.

"This bill does not take over the role of the private plans," said Sen. Ron Wyden, D-Ore. "The question is, should we make it possible for the secretary of Health and Human Services to complement the role, to go beyond it and say that there are some circumstances where we should negotiate?"

The House of Representatives passed a more ambitious bill earlier in the year that requires the secretary of HHS to negotiate drug prices, but Sen. Max Baucus, D-Mont., noted that the measure would not get the votes needed to overcome a filibuster in the Senate. Instead, he called for just lifting the restriction that bars government negotiations under Medicare. Even that alternative fell short Wednesday.

Democrats called the ban on government negotiations a favor to special interests groups.

"Time and again, the interests of the drug industry are put ahead of the interests of the elderly," said Sen. Edward M. Kennedy, D-Mass.

But Republicans said the drug benefit, also called Medicare Part D, is a testament to the idea that the private market works and that "government-run health care is not the answer."

"Why do supporters of this legislation hate the Medicare drug benefit so much? They hate it because nothing could be more damaging to the idea of government run health care than Part D," said Sen. Charles Grassley, R-Iowa.

The AARPsaid it would continue to push for allowing government negotiations, despite slim prospects for passage in the Senate.

"Senators should know this issue is not going away," the advocacy group said. "No amount of campaign money can trump the will of 90 percent of Americans."