WASHINGTON » Some of President Barack Obama’s closest advisers are rethinking their plans to leave the White House, both to help him regain his political standing and to avoid perceptions that staff members are either escaping or being forced out in a time of duress.

Among them are Alyssa Mastromonaco and Rob Nabors, both deputies to the White House chief of staff, Denis R. McDonough. Mastromonaco and Nabors have been with Obama from the beginning of his presidency, and Mastromonaco since the start of his Senate career. Both had wanted to leave at the end of the year but have decided to stay indefinitely, officials said.

Others who have indicated that they have put off their departures include the White House counsel, Kathryn Ruemmler, and Gene B. Sperling, who as director of the National Economic Council is Obama’s chief economic adviser. Jeanne Lambrew, an architect of the Affordable Care Act, had also been hoping to leave but might remain for months more, according to officials familiar with her thinking.

In any White House, the end of the year typically brings staff changes, especially as exhaustion sets in during the later years of an administration. But the Obama team has been as tested as any in decades: by economic calamity, the winding down of two wars, an expansive domestic agenda, various international crises and, lately, the trouble-filled execution of the most ambitious health care program since Medicare.

Controversy over the health care law has helped drive Obama’s approval ratings to new lows, a trend that the White House is scrambling to reverse. Longtime aides who stayed with the president into the second term — thinking that they would remain for months or a year to help with the transition — are now feeling pressured to extend their service, officials said.

"Everybody is sensitive to making sure that you don’t put the president in a position where he doesn’t have a team," said one official, who like others interviewed declined to be identified while discussing personnel issues that are fraught with political overtones. "We’re not at war with each other. We actually like each other, and we are loyal to the president."

And at a time when White House critics are looking for Obama to fire someone after the debacle over the health care website, "none of us want to look like we’re being forced out," the official said.

Mastromonaco, 37, the deputy chief of staff for operations, had long talked privately of leaving by 2014, said those familiar with her thinking, but she has been reconsidering her decision after discussions with Obama. She recently took just two days off to marry David Krone, the chief of staff to the Senate majority leader, Harry Reid.

Nabors, 42, who is the deputy chief of staff for policy, had been less open about his plans but was contemplating leaving after this year, officials said. He is responsible, in particular, for strategy on the budget and climate change and has been pressed by the president and McDonough to significantly extend his service.

Mastromonaco was among the young aides who joined Obama’s presidential campaign in 2007. She had been Obama’s Senate scheduler and director of his fundraising committee. In the campaign, she directed scheduling and advance work for his appearances, a job she then held in the White House before her promotion three years ago to deputy chief of staff.

Mastromonaco grew closer, personally and politically, to the president over time, associates say, and her broad responsibilities grew to include advice on strategy. She often stood out in an overwhelmingly male inner circle; in the famous photo of Obama and senior aides monitoring screens on the night Osama bin Laden was killed, Mastromonaco can be seen in the far rear, the only woman pictured other than Hillary Rodham Clinton, then the secretary of state.

Nabors, who is black, contributed to the diversity of an Obama team that has been criticized as too white. A longtime senior aide to House Democrats, he joined the Obama team after the 2008 election as the chief liaison to Congress. He was promoted with Mastromonaco to be deputy chief of staff in 2011.

The advisers’ change in thinking has also been prompted by the announcement of other departures. In particular, the departure of Pete Rouse, 67, Obama’s lowest-profile but longest-serving Washington adviser, will leave a void that will take several aides to fill given Rouse’s broad contacts and expertise, say Democrats in the administration and on Capitol Hill. Rouse, who will leave by Jan. 1, has worked especially closely with Mastromonaco and Nabors.

The decisions to stay on have also come despite the news that John Podesta, a former chief of staff to President Bill Clinton, was joining as counselor for a year to help right the administration’s course.

Sperling, 54, agreed to stay as economic adviser at least a month longer, until February, to oversee planning for Obama’s State of the Union address and annual budget. The delay buys time for Sperling’s successor, Jeffrey D. Zients, to make the transition from his temporary job as the fix-it manager for the Healthcare.gov website. On Wednesday, Zients turned over that job to Kurt DelBene, a former Microsoft executive.

The White House counsel, Ruemmler, will stay at least into early spring, officials say, to help Obama choose a successor.

Lambrew, the health policy aide, had been planning to leave as deputy director of the White House Domestic Policy Council before the bungled Oct. 1 rollout of the health insurance website, according to people close to her. The hiring last summer of Chris Jennings, a former top Clinton White House adviser, to help with the health care program made Lambrew’s departure more likely, officials said, yet they urged her to stay on to help with the repair effort.

A longtime health policy expert, Lambrew had joined the Department of Health and Human Services at the start of the administration and later moved to the White House. A 2010 memo to White House officials from David Cutler, a Harvard professor and health care expert, expressed concerns that critics inside and outside the administration have discussed privately.

He wrote that Lambrew "is not known for operational ability, knowledge of delivery systems or facilitating widespread change." He added, "The fact that Jeanne and people like her cannot get along with other people in the administration means that the opportunities for collaborative engagement are limited."

Lambrew and a White House spokeswoman did not respond to requests for comment. But one official said Lambrew is resigned to the fact that her departure will inevitably be linked to the flaws of the health care program, despite her longtime intention to leave.

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Jackie Calmes And Michael D. Shear, New York Times

© 2013 The New York Times Company