With No Confirmed Medicare Chief for 6 Years, Obama Tries Again

President Obama has renominated Marilyn B. Tavenner to run the agency in charge of Medicare and Medicaid, and his action provided a reminder that the agency has been without a Senate-confirmed chief for more than six years.

By any measure, the agency has huge responsibilities. Medicare and Medicaid provide health care to more than 100 million people. They spent more than $800 billion last year, accounting for 23 percent of the federal budget. They are at the center of the looming fiscal fight between Mr. Obama and Republicans in Congress.

Ms. Tavenner is now the acting administrator of the agency, the Centers for Medicare and Medicaid Services. The agency has the primary responsibility for carrying out the 2010 health care law, which is expected to provide coverage to 30 million people who are uninsured.

It is unclear how hard Mr. Obama will push the Senate to confirm Ms. Tavenner, a nurse and former Virginia state official.

Ms. Tavenner worked for mor than two decades at the Hospital Corporation of America, first as a nursing supervisor, then as a hospital executive and eventually as president of the company’s outpatient services group.

Dr. Donald M. Berwick, who led the agency under a recess appointment from July 2010 to December 2011, said it was irresponsible for the Senate to allow a vacancy to continue.

“An agency of this importance and complexity needs stable leadership,” Dr. Berwick said in an interview on Friday. “Senators, even those who disagree with the president, need to look in the mirror and see if they are acting responsibly. They have a responsibility to see that the government runs well, even if they disagree with the administration.”

The Senate Finance Committee never held a confirmation hearing for Dr. Berwick, a health policy expert who became a symbol of all that Republicans disliked in the new health care law.

Ms. Tavenner is more of a manager and less of a visionary. She has support from many Democrats and some Virginia Republicans, including Representative Eric Cantor, the House majority leader, who has described her as “eminently qualified.”

The American Medical Association, the American Hospital Association and Families USA, a consumer group, endorsed Ms. Tavenner on Thursday, saying she had done a good job in 14 months as acting administrator.

Senator Orrin G. Hatch, Republican of Utah, said he had met with Ms. Tavenner and found her to be “smart and diligent.’’ But he added, “There are many questions she’ll need to fully answer before I decide whether or not to support her nomination.”

Debate on the nomination will give Republicans a fresh opportunity to assail the health care law, and Democrats are not eagr to fight that battle again.

Congressional Republicans have flooded the administration with hundreds of questions about how it is carrying out the law. Some Republicans vow to hold up Ms. Tavenner’s nomination unless they get answers.

In his first term, Mr. Obama made health care one of his top priorities. He said the cost of Medicare and Medicaid was “the biggest threat” to the nation’s fiscal future. But he did not name anyone to lead the agency until April 2010, after he had signed the Affordable Care Act.

One effect of vacancies at the top of the agency is to give the White House more control over the nation’s biggest health programs, Medicare officials said.

Mr. Obama first nominated Ms. Tavenner in December 2011. Finance Committee aides said they were waiting for the White House to submit paperwork for Ms. Tavenner, including copies of a questionnaire and recent tax returns. The panel plans to hold a hearing next week on the nomination of Jacob J. Lew to be T! reasury s! ecretary.

Undaunted by his experience in Washington, Dr. Berwick remains a man with a mission. “I am close to a decision on running for governor of Massachusetts,” he said. “I’m giving it strong consideration. I am very interested in the possibility that states can lead reform on health care and other issues.”