Transportation Secretary Ray LaHood announced Tuesday he will not be sticking around for President Barack Obama’s second term.

There was no immediate word from the White House about a successor to the former Republican congressman, who informed department employees in an email that he had told the president he would be leaving.

“I plan to stay on until my successor is confirmed to ensure a smooth transition for the department and all the important work we still have to do,” said LaHood, who represented Illinois in the House for seven terms.

LaHood called the post “the best job I’ve ever had” and said he was proud of the “significant” achievements during his tenure.

His accomplishments included a central role in negotiating a landmark agreement that will double the fuel economy of the nation’s automobiles by 2025.

LaHood also spearheaded efforts to reduce distracted driving and was responsible for managing the $48 billion in transportation investments that were part of the 2009 stimulus (PL 111-5), including the popular “TIGER” program that supports a variety of competitive transportation and infrastructure project grants.

“I want to thank Secretary LaHood for his dedication, his hard work, and his years of service to the American people — including the outstanding work he’s done over the last four years as Secretary of Transportation,” Obama said in a written statement. The president said LaHood fought to create jobs through investments in roads, bridges and transit systems.

“Under his leadership, we have made significant investments in our passenger rail system and laid the groundwork for the high-speed rail network of the future,” Obama said. “And every American who travels by air, rail or highway can thank Ray for his commitment to making our entire transportation system safer and stronger.”

LaHood’s fight against distracted driving became a personal crusade. He spoke out about the dangers of texting or using mobile phones while behind the wheel and oversaw a “Faces of Distracted Driving” campaign that chronicled stories of lives lost.

His tenure was also an exercise in trying to execute the administration’s ambitious policy agenda — including the push to develop a nationwide high-speed passenger rail system — despite broad opposition by the Republican-controlled House. When several Republican governors rejected federal high-speed rail funds, for example, LaHood steered the money to other states willing to spend it on rail infrastructure.

LaHood stumbled in the early days of the new administration, when he commented that switching from the current motor fuels taxes to a fee based on the number of miles a vehicle is driven was a concept worth exploring. The White House, sensitive to GOP claims that it wanted to raise taxes on motorists and that a vehicle-mileage tax would infringe on the privacy of motorists, publicly rebuked LaHood, who had to walk back his comments. The surface transportation authorization (PL 112-141) eventually enacted last year included no changes in motor fuels taxes and instead supplemented a funding shortfall with general tax revenue — leaving LaHood’s successor with the job of trying to negotiate a long-term fix for the surface transportation funding system.

LaHood’s departure from the administration had been expected, although the secretary had suggested since the election that he might be willing to stick around longer if Obama wanted.

Among those thought to be under consideration is Los Angeles Mayor Antonio Villaraigosa, a Democrat who has pushed for major infrastructure investments in Southern California. As a Latino, Villaraigosa would help address criticism that Obama’s second-term cabinet appointments so far have been skewed toward white males. The mayor championed a Los Angeles County transportation plan last year that included a sales tax increase, which garnered majority support among voters but narrowly missed the two-thirds threshold needed to pass.

Former Pennsylvania Gov. Ed Rendell, cochairman of the Building America’s Future coalition with New York City Mayor Michael Bloomberg, is considered by some lobbyists and industry observers as a strong possibility, given his recent work on transportation development.

Former House Transportation and Infrastructure Chairman James L. Oberstar, a Minnesota Democrat who lost his re-election bid in 2010, has expressed interest, though he was publicly critical of the administration for not backing his proposed surface transportation bill in 2009. Recently retired Rep. Steven C. LaTourette, a moderate Ohio Republican with close ties to Speaker John A. Boehner, is another industry and lobbyist favorite.

Nick J. Rahall II of West Virginia, the ranking Democrat on the House Transportation and Infrastructure Committee, said anybody who is chosen should be cut from LaHood’s bipartisan mold.

“Four years ago, my good friend Ray LaHood put party politics aside in order to help modernize our transportation infrastructure and speed our economic recovery,” Rahall said in a statement.