Sen. Bob Corker, R-Tenn. (center), talks to reporters on Capitol Hill. He decided Tuesday not to seek a third term. Corker is the first Senate retirement of the 2018 election cycle.

Sen. Bob Corker of Tennessee, chairman of the influential Foreign Relations Committee, will not seek re-election in 2018.

He is the first senator to announce retirement plans ahead of next year’s election cycle.

“I also believe the most important public service I have to offer our country could well occur over the next 15 months,” Corker said in a statement, “and I want to be able to do that as thoughtfully and independently as I did the first 10 years and nine months of my Senate career.”

That could well be an allusion that Corker may speak out more in areas where he may disagree with President Trump.

Corker also hinted that his political career may not be over.

“I know that we will continue to have an impact for the remainder of our term,” Corker said, “and I look forward to finding other ways to make a difference in the future.”

Corker, 65, the former mayor of Chattanooga, Tenn., has been a steadfast conservative in his votes but moderate in his tone, from making a mark on the auto bailout to playing a key role in the consideration of authorization of force in Syria during the Obama administration.

He embraced Trump during the campaign and was even said to be in the running for secretary of state before the job instead went to former Exxon Mobil CEO Rex Tillerson.

But Corker’s relationship with the president has soured somewhat. In May, he referred to the administration as being in a “downward spiral” that Trump needed to get “under control.”