Sen. Bob Corker said Tuesday he will not seek re-election next year.

“After much thought, consideration and family discussion over the past year, Elizabeth and I have decided that I will leave the United States Senate when my term expires at the end of 2018,” the Chattanooga Republican said in a statement.

“When I ran for the Senate in 2006, I told people that I couldn’t imagine serving for more than two terms. Understandably, as we have gained influence, that decision has become more difficult. But I have always been drawn to the citizen legislator model, and while I realize it is not for everyone, I believe with the kind of service I provide, it is the right one for me.

“I also believe the most important public service I have to offer our country could well occur over the next 15 months, 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.

“Serving the people of Tennessee in this capacity has been the greatest privilege of my life. And as I spent the month of August traveling across our great state, I was reminded that we live in a unique place full of people who care deeply about the direction of our country.”

Corker, a two-term senator who chairs the influential Senate Foreign Relations Committee, had agonized for weeks over whether he should run for another term amid speculation that he would likely face a challenge from the GOP’s right flank.

<p>U.S. Senator Bob Corker, R-Tenn., speaks during the Tennessee Farm Bureau President's Conference on Thursday, August 11, 2016, in Franklin, Tenn.</p>

Conservative activist Andy Ogles already has announced his intentions to run for the seat. Other Republicans, including former state Rep. Joe Carr and state Sen. Mark Green, also have said they are may jump into the race.

Corker remained undecided about his political future as recently as two weeks ago, when he said that, while there was still work to do, “running for re-election has never been an automatic for me.” A few days later, he promised that a decision would come “very, very soon.”

His announcement that he won't run for another term follows his unusual – and very public – airing of grievances with President Donald Trump earlier this summer.

The two traded jabs in August after Corker, following Trump’s much-criticized response to the deadly violence in Charlottesville, Va., told reporters that Trump had not yet shown the stability nor some of the competence needed to become successful.

A week later, Trump fired back at Corker on Twitter, calling Corker’s statement strange “considering that he is constantly asking me whether or not he should run again in '18.”

“Tennessee not happy!” Trump exclaimed.

MORE: President Trump lashes back at Sen. Corker: 'Tennessee not happy!'

Corker, who earlier had been considered as Trump’s vice presidential running mate and secretary of state, insisted his relationship with Trump had not been harmed by the exchange.

A little more than a week ago, the two met for more than an hour in the Oval Office in what spokesmen for both men described as a productive discussion on a broad range of foreign and domestic issues. At that meeting, Trump encouraged Corker to run for another term.

Corker, a former Chattanooga mayor, was first elected to the Senate in 2006, defeating Democrat Harold Ford Jr. of Memphis in an otherwise difficult election season for the GOP. Republicans lost their majorities in both the Senate and the House that year. Corker was the only Republican newcomer to win a Senate seat that year.

In the Senate, Corker quickly developed a reputation as lawmaker who would side with then-President George W. Bush on some issues, but challenge him on others. For example, Corker backed an energy bill that his fellow Republicans tried to kill. He also went against the White House and supported the expansion of a health insurance program for children.

Corker was easily re-elected in 2012 against Democrat Mark Clayton, an anti-gay activist denounced by his own party.

When Republicans reclaimed their Senate majority two years later, Corker became chairman of the Senate Foreign Relations Committee, a job that elevated his profile on the national stage and put him at the center of national and international issues.

U.S. Senator Lamar Alexander released the following statement after Corker's announcement:

“Even when he’s been investigating smugglers’ tunnels near the Gaza strip, talking to foreign leaders, or giving advice to President Trump, Bob has never let his feet leave the ground in Tennessee. He says what he thinks, does what he believes is best for Tennesseans, and has helped lead his colleagues on complicated issues involving the federal debt and national security. His absence will leave a big hole in the United States Senate, but I know he’s carefully weighed his decision, and I’m looking forward to seeing what he tackles next.”