WASHINGTON (AP) — Hoping to make the third nomination the charm, the White House announced Monday that President Barack Obama would nominate FBI Deputy Director John Pistole to head the Transportation Security Administration.

In a statement, Obama said Pistole’s work with the FBI makes him a valuable asset to the administration’s efforts to strengthen security and screening measures at the nation’s airports.

Obama has struggled to fill the top job at TSA, the agency whose primary mission is to shore up the nation’s defenses against terrorist threats in the air, on roads and rails. The Obama administration has called the job the most important unfilled position on the president’s team.

Obama’s first choice for the post, Erroll Southers, withdrew his nomination after it became apparent he would have trouble winning confirmation. Questions were raised about a reprimand that Southers, a top official with the Los Angeles Airport Police Department, had received for running background checks on his then-estranged wife’s boyfriend two decades ago. He acknowledged giving Congress inconsistent answers on the matter.

Obama later nominated Retired Army Maj. Gen. Robert Harding for the job, but he too took himself out of the running in March. Harding had extensive intelligence experience that Obama hoped to tap in fortifying security against attacks such as the Christmas Day bombing attempt on an airliner bound for Detroit. But Harding’s past as a defense contractor raised complications for his nomination.

Pistole began his career with the FBI in 1983, rising through the ranks of the agency’s counterterrorism division. He’s served as deputy director since 2004.

The FBI works hand-in-hand with TSA in screening travelers at the nation’s airports. Those procedures have come under scrutiny following both the Christmas Day incident and the attempted bombing in Times Square earlier this month.

While the FBI put the suspect in that incident, Faisal Shahzad, on the government’s “no-fly” list, he was still able to buy a plane ticket and board a flight to Dubai from New York’s John F. Kennedy Airport. He was arrested on the plane shortly before take-off.

An administration official told The Associated Press at the time that the FBI asked TSA not to call airlines directly to tell them an important name had been added to the list.

Pistole’s nomination won praise Monday from some lawmakers on Capitol Hill, including Maine Sen. Susan Collins, the top Republican on the Senate Homeland Security and Governmental Affairs Committee. In a statement, Collins said she was pleased the president had chosen a nominee with “strong law enforcement experience.”