WASHINGTON — A buildup of bipartisan opposition on Capitol Hill, along with negative reactions from patient groups, businesses, insurers and others, convinced the Centers for Medicare and Medicaid Services (CMS) not to proceed “at this time” with several controversial changes to the Medicare Part D prescription drug program.

A CMS draft regulation that had been released in January would have a wide-ranging impact on the Part D program, including new limits on the number of plans insurers could offer consumers and new rules about what drugs those plans must cover. It also would prohibit exclusion of pharmacies from a plan’s “preferred pharmacy network” as long as the pharmacies agreed to the plan’s terms and conditions.

During the rule’s comment period, which closed March 7, CMS received “numerous concerns about some elements of the proposal” from lawmakers and stakeholders, CMS administrator Marilyn Tavenner said in a letter to Congress.

“Given the complexities of these issues and stakeholder input, we do not plan to finalize these proposals at this time,” Tavenner said.

Nevertheless, she said, the agency will move forward with other elements of the rule, including those aimed at ensuring access for beneficiaries during natural disasters, reducing fraud and broadening the release of Part D data that does not identify beneficiaries.

Critics said the changes, if adopted in coming months, could not only undermine Part D benefits but also impact drug benefits available through Medicare Advantage, a program that allows Medicare beneficiaries to obtain their major medical coverage through private insurers.

Although the proposals were opposed by both Republicans and Democrats in Congress, the former had already begun to look for ways to leverage popular anger over the changes into campaign attacks on Democratic incumbents who could be vulnerable in November’s election.

Critics of the proposed changes said the government had effectively agreed to start over in the face of broad, bipartisan opposition.

“We applaud CMS administrator Tavenner for the agency’s sound judgment on this issue,” said Mary Grealy, president of the Healthcare Leadership Council, a coalition that represents chief executives from the health care industry.

But others noted that the move curtails a proposal to broaden pharmacy access and could hurt Medicare beneficiaries in rural areas and underserved neighborhoods who might have benefited from the change.

The new rules had called for ending a requirement that insurers offer coverage for all drugs classed as antidepressants and as immunosuppressants (which are used in transplants). CMS was contemplating a similar change for antipsychotics after 2015.

In addition, the proposals had called for broadening the number of pharmacies covered by health plans while limiting the choice of Medicare Part D policies available in any given ­region.

“We are deeply disappointed in CMS’ decision not to move forward at this time with the pharmacy choice provision,” said B. Douglas Hoey, chief executive officer of the National Community Pharmacists Association.