John Pistole has been the Transportation Security Administration chief since June 2010.

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NEW: Pistole is nominated to be president at his alma mater, Anderson University

TSA chief John Pistole surprises agency employees with announcement

Under Pistole, TSA backed off plan to allow small knives, other items back on flights

Lawmakers, union praise Pistole's leadership at TSA

Washington CNN  — 

Transportation Security Administration chief John Pistole said Thursday he will resign at the end of the year, ending his run as the longest-serving administrator of the government agency entrusted with keeping terrorists off planes, trains and other means of transport.

Pistole, 58, who was the FBI’s deputy director before joining the TSA more than four years ago, made the surprise announcement to employees at a town hall meeting, which was broadcast to TSA facilities nationwide. He has been nominated to become president of Anderson University, a private Christian university in central Indiana where he earned his undergraduate degree in 1978.

During his tenure, Pistole became a forceful advocate of “risk-based security” in which the government sought to mitigate risks by taking certain precautions and of the TSA’s PreCheck program, which employed that philosophy to reduce checkpoint lines.

But risk-based security also factored into his most public misstep. In 2013, Pistole announced the TSA would allow small knives and certain other banned items onto aircraft, saying their risk had been mitigated by locked cockpit doors. The change would have brought the United States into alignment with other countries that allow such items.

The knife announcement met with an instant and furious response from flight attendants, pilots, passengers and lawmakers. The TSA pulled back the plan shortly before it was to take effect and later abandoned the idea altogether.

TSA drops plan to allow small knives on planes

On Thursday, some members of Congress and employee groups lined up to give accolades to Pistole.

U.S. Rep. Bennie Thompson, D-Mississippi, ranking member on the House Committee on Homeland Security, cited Pistole for his work on the PreCheck program and for his decision to allow airport screeners the right to bargain collectively.

The American Federation of Government Employees, which represents 45,000 airport screeners, said Pistole’s efforts had led to “advances in safety, working conditions, and morale.”

Pistole became administrator in June 2010.

In a statement Thursday, Pistole thanked TSA employees for their work. “I could not be more proud of all that our employees have accomplished together, particularly what they have done to help enhance the effectiveness and efficiency of transportation security while improving the passenger screening experience.”