WASHINGTON -- President Barack Obama on Monday nominated a new head of the Transportation Security Administration, a retired Army general and intelligence expert who would oversee the nation's airline passenger screening system.

Robert A. Harding would be the fifth person in nine years to head the agency and, if confirmed, would arrive as the Obama administration adjusts security operations in the wake of the attempted Christmas Day airliner bombing.

The White House hopes that Mr. Harding, 61, can win quick confirmation after months of delays and controversy plagued the previous nominee, Erroll Southers, a onetime FBI agent who recently left his post as assistant chief of airport police in Los Angeles.

"The TSA administrator is among the most important unfilled posts in the Obama administration," said Homeland Security Secretary Janet Napolitano, who announced the nomination Monday. "If there were ever a nominee that warranted expedited, and detailed, consideration in the Senate, this is it."

Republicans said they looked forward to meeting Mr. Harding but did not indicate whether they would support his nomination.

TSA has been operating under an acting administrator for months. Republican lawmakers voiced concern over conflicting accounts given by Mr. Southers about a past episode in which he accessed a federal database to get information about the boyfriend of his estranged wife. Mr. Southers' nomination also was stalled by GOP worries that he would allow TSA employees to have collective-bargaining rights. He withdrew himself from consideration a few weeks ago.

Mr. Harding's nomination comes as officials try to fix systemic gaps that let a would-be bomber board a Northwest airliner last Christmas.

In a statement, Mr. Obama touted Mr. Harding's credentials. "Bob's talent and expertise will make him a tremendous asset in our ongoing efforts to bolster security and screening measures at our airports," the president said. "I can think of no one more qualified than Bob to take on this important job, and I look forward to working with him in the months and years ahead."

Mr. Harding, who would be the TSA's first black administrator, has had a lengthy career in intelligence work. He served 33 years in the Army, commanding a counterintelligence battalion in Korea and heading counterintelligence operations at Fort Meade, Md., and in staff positions around the world.

He rose to become the Pentagon's senior human intelligence officer and, later, a top official at the Defense Intelligence Agency. Mr. Harding retired as the Army's No. 2 intelligence official in 2001.

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