As Bank of America scrambled to appoint a new chief executive, one of the bank’s longtime soldiers — Brian Moynihan — stood by ready and willing to take a job that others had turned down.

It was a familiar role for Moynihan, who has had a career of falling into bigger jobs at the bank when executives were fired or shunted aside. Now, he faces his toughest challenge: rebuilding Bank of America’s image after a year marred by the stigma of a taxpayer bailout, lawsuits by shareholders unhappy with its marriage to Merrill Lynch, and investigations into the bank’s failure to disclose losses at Merrill Lynch and billions in bonuses it paid out just before the deal.

“He needs to redefine who they are,” said Mark Williams, a finance professor at Boston University and a former bank examiner for the Federal Reserve. “I think they’ve lost who they are.”

Moynihan has worked in a broad range of the bank’s businesses. But his experience in each unit has been brief. In recent years, as the bank pushed out a series of executives, Moynihan was on hand to step into their roles. When trouble hit the investment banking unit in 2007, he moved into the breach. Late last year, when the bank fired its general counsel, Moynihan was appointed as his replacement. And this year, he held two different jobs as a result of executive departures.

His rapid rotation has hardly gone unnoticed. “Many of you know him because he’s been in so many different jobs,” retiring CEO Kenneth Lewis told employees at a town hall meeting Wednesday to announce Moynihan’s appointment.

“And so hopefully, he will be in this job much longer than the last three or four.”

Although Moynihan, 50, was among the bank’s top internal candidates to fill Lewis’ shoes, Bank of America’s board first sought an outside candidate who could turn a new page.

The board was unable to woo Robert Kelly, the chief executive of Bank of New York Mellon and a figure who would have been removed from the furor associated with the bank’s acquisition of Merrill Lynch. The other candidate, Gregory Curl, a bank insider, was knocked out of the running amid an investigation by the attorney general of New York over the Merrill deal.

That has not been lost on observers who say the bank would fare better under a chief executive with longer experience. “I was disappointed that the board didn’t go outside and get someone with deeper talent and experience, and more risk management experience,” Williams said.

To some members of Bank of America’s divided board, Moynihan made a good compromise: He never moved from Boston to the bank’s headquarters in Charlotte, N.C., and his relative newness to the bank appealed to directors who wanted a fresh start. For directors who wanted a company insider, Moynihan had enough experience within the bank to be able to retain executives and keep the company on its current path.

Under pressure

Moynihan declined through a spokesman to be interviewed. But in an interview last week, he spoke about his vision of turning Bank of America into a more consumer-friendly bank. The nation’s largest lender is shifting away from simply selling customers as many products as it can, he said, to trying to match products to the needs of consumers.

“We build a product around your usage pattern, not around ours,” he said. “Customer-centric is you sell a checking account, you sell a savings account. You set up a credit card. Customer-centric is, how do you integrate that card product into what people want?”

The bank is under unprecedented pressure from the government to make new loans, modify old ones, and create products that are transparent and fair. Bank of America has long minted money from its consumer bank in part from fees on a variety of transactions, and some of that revenue will be lost because of tighter regulation.

At the same time, Moynihan will have to navigate a maze of regulators that want the bank to hold more capital and take greater care to avoid making loans that will sour in areas like credit cards and mortgages.

Moynihan began his career as a lawyer, not a banker. He joined the bank as part of a merger.

At FleetBoston, which Bank of America acquired in 2004, he rotated in and out of roles, from running the commercial lending unit to a corporate strategy post. After the deal, he was one of only a handful of senior executives to land a spot on the management team of Lewis, at first as the head of wealth management.

Moynihan was an unpolished speaker but strong manager who was willing to parachute into sticky situations — much like his new boss. Since 2004, he has earned $59 million in take-home pay at the bank, according to Equilar, a compensation research firm.

Although he also took a turn as the bank’s general counsel, the bank did not mention it in its news release announcing his appointment. Instead, it said he had run investment banking from 2007 to 2009. But he served as general counsel just as the bank closed its merger with Merrill and negotiated its second bailout, which has been scrutinized by Congress. The attorney general of New York and the Securities and Exchange Commission are investigating the merger.

The change in the bank’s leadership comes one week after the bank repaid the full $45 billion in bailout funds that it received from the government.

The bank’s board did not reach an agreement on Moynihan’s pay, which is under the supervision of the Treasury Department’s pay regulator until the end of the year.

Pursuing a vision

Purna Saggurti, the co-head of global corporate and investment banking, described Moynihan as humble and self-effacing. In an interview, he recalled a meeting in the summer when Moynihan said to a group of his managers: “We need to be wise, not smart.”

In the town hall meeting, Moynihan said his goal for the bank is to execute the vision of Lewis.

“Think about what we have: the No. 1 position in every relevant product there is in financial services throughout the world,” Moynihan said. “We can actually fulfill the mission that Ken gave us because we can be the most admired to every customer.”