WASHINGTON (AP) — When a federal program that promised cash rebates to people who traded in their clunkers for more fuel-efficient vehicles was overrun by demand, President Barack Obama assigned Jeffrey Zients, his deputy budget director, to help eliminate the backlog.

When the same thing happened with sign-ups for an updated version of the GI Bill, one designed to help the 9/11 generation of veterans get a college education, Obama again turned to Zients for help.

Now, as Obama's health care website continues to be plagued by a rash of technical problems that have turned it into an administration embarrassment and a source of frustration for uninsured people trying to sign up for coverage that the law now requires many of them to have, who has Obama called for help? Zients, his Mr. Fix-it.

Faced with mounting questions about the website, the Obama administration announced Tuesday that the longtime management consultant will help fix the problems and turn the site into the breezy, one-stop shopping portal Obama promised it would be.

Zients came out of a temporary retirement from the federal government and quietly dived into his new assignment on Monday. He left the administration earlier this year after the budget director's job went to someone else. Last month, Obama announced that Zients would take over next year as director of the National Economic Council, becoming the president's chief economic adviser.

Zients will provide short-term advice, assessments and recommendations to a Department of Health and Human Services team that officials say has been working around the clock to fix www.healthcare.gov since it went live Oct. 1. Administration officials, from Obama on down, had promoted the federal website as the first stop for uninsured people in 36 states who want to figure out what coverage they can afford. They are now urging people to also try signing up by telephone, mail or in person.

Zients has led some of the country's top management firms, advising companies worldwide.

He joined the administration in 2009 as deputy director of the Office of Management and Budget and the nation's first chief performance officer. He also served two stints as OMB's acting director, and led an effort to streamline government and save money by selling off unused or underused real estate. The effort stalled in Congress.

Zients was acting OMB director from January 2012 through April 2013, when the Senate confirmed Sylvia Mathews Burwell for the director's post.

By many accounts, the 46-year-old Zients, who lives in Washington with his wife and four children, is well-respected and liked inside the White House.

"I think that's why he's continually being handed tough jobs," said Kenneth Baer, who was a senior adviser to Zients at the budget office.

Zients grew up in the Washington area and spent his career in business before agreeing to work for Obama. That two decades of experience allowed him to bring a different perspective to government and how it should be run, Baer says.

"He's not going to be looking under the hood and tell you, 'I can fix the coding, I can fix it,'" Baer said of Zients' newest assignment. "His skill is going to be how to identify challenges, prioritize what solutions need to be done next, assessing what talent is already available and then how to motivate them to do that job as quickly and as ably as possible."

Aneesh Chopra, who was Obama's chief technology officer, said Zients is extremely skilled in figuring things out from a management perspective.

"If I was confident this issue would be resolved before his participation, I am doubly so now," said Chopra, who also worked with Zients at the Advisory Board Co., one of two business advisory firms where Zients has held top posts. "Jeff's track record is really a relentless focus on execution."

In 2009, after far more drivers than anticipated signed up for the Cash for Clunkers program and the federal website set up to process rebates of up to $4,500 per new car kept crashing under the weight of the demand, Zients helped smooth things out.

He played a similar role following the rocky rollout of a new GI Bill for veterans of the wars in Iraq and Afghanistan. The program had become so bogged down that the Veterans Affairs Department began to issue $3,000 advance checks to thousands of veterans who needed help paying expenses until their claims could be processed. At one point, Zients, Chopra and Vivek Kundra, then the chief technology officer, flew to a VA processing center in St. Louis to size up the problems.

Before Zients joined the administration, he was chief executive officer and chairman of the Advisory Board Co., and chairman of the Corporate Executive Board. Zients also founded Portfolio Logic, an investment firm that focused on business and health care service companies.

Zients has a political science degree from Duke University.