WASHINGTON, D.C. — Transportation Secretary Ray LaHood, the only Republican still in President Barack Obama’s first-term Cabinet, said Tuesday he plans to leave the Obama administration.

LaHood, a former congressman from Illinois, pushed for greater safety on the highways and in the air. He led the Transportation Department throughout Obama’s first term and helped steer a number of safety measures and highway projects, including steps to curb distracted driving, promote high-speed rail and repair roads and bridges. Under his watch, the department demanded tougher fuel efficiency requirements for automakers and took steps to address airline pilot fatigue.

LaHood said in an interview with The Associated Press that he told Obama a week after the November election that he needed to move on but said he was still “conflicted” by his decision because he liked working for Obama and considered it the “best job I’ve ever had in public service.”

He said he plans to remain at the department until his successor is confirmed by the Senate, which he expected in about two months. The only other Republican who was in Obama’s first-term Cabinet was Defense Secretary Robert Gates, who stepped aside and was replaced by Democrat Leon Panetta earlier.

LaHood said he would not run for public office in his home state of Illinois and said he did not have any specific plans.

“I have had a good run. I’m one of these people who believe that you should go out while they’re applauding,” he said. LaHood said he was content to watch from the sidelines as his oldest son, Darin, serves in the Illinois state senate.

Obama is remaking his Cabinet at the beginning of his second term with the departures of Secretary of State Hillary Rodham Clinton, Panetta and Treasury Secretary Timothy Geithner. In addition to LaHood, the heads of the Interior and Labor departments also have announced their resignations in recent weeks.

The Transportation Department has carried a bipartisan imprint in recent years and been the place for a president to ask a member of the opposing party to serve. Former Rep. Norman Mineta, a California Democrat, served as Transportation secretary during the administration of President George W. Bush. Obama has nominated former Nebraska Sen. Chuck Hagel, a Republican, to serve as defense secretary to succeed Panetta.

Possible replacements for LaHood include Los Angeles Mayor Antonio Villaraigosa, who has pushed for increased rail service in Los Angeles and served as chairman of last year’s Democratic National Convention, and Debbie Hersman, the chairman of the National Transportation Safety Board. The name of former Rep. Jim Oberstar of Minnesota, who led the House Transportation and Infrastructure Committee, has also been mentioned.

LaHood, 67, served seven terms in Congress representing a central Illinois district that includes his hometown of Peoria, Ill., and overlapped with Obama in the state’s delegation during the last four years of his career.

At the department, LaHood provided a bipartisan voice during the first term, helping implement billions of dollars in transportation projects from the 2009 economic stimulus bill and promoting the plan to wary Republicans. The department pushed forward thousands of infrastructure projects to improve roads and bridges and LaHood worked with Congress last year to pass an overhaul of highway and transit programs that gives states more flexibility in how they spend federal money.

He tackled a number of regulations that had been mired in gridlock. LaHood worked with auto makers and environmentalists to develop tougher fuel efficiency standards for new cars, with the goal of providing environmental benefits and reducing fuel consumption.

Guarding against airline pilot fatigue, the Federal Aviation Administration set new rules under LaHood’s watch that would limit the maximum time a pilot can be scheduled on duty and place limits on scheduled flying time and hours for pilots flying overnight. The action was prompted by a deadly plane crash near Buffalo, N.Y., that raised concerns about pilot fatigue.

LaHood also has taken on major transportation companies during his tenure, slapping Toyota Motor Co. with record fines for delaying safety recalls and failing to promptly report problems to federal regulators.

He recently ordered United Airlines to ground its Boeing 787 Dreamliner following mishaps with the aircraft’s batteries. The FAA is investigating the cause of the problems to the Dreamliner, which uses lithium ion batteries and is the world’s first airliner whose structure is made mostly from lightweight composite materials.

Perhaps LaHood’s most passionate work has involved distracted driving, which he has called a “national epidemic.” He has launched a national media campaign to end texting and cellphone use by drivers, an awareness campaign that has drawn comparisons to efforts to promote seat belt use more than a generation ago.

The grandfather of 10, LaHood has often emphasized the toll that deaths and injuries from distracted driving can inflict on families.

“Safety will be something that people will remember us for in all modes of transportation,” LaHood said.