CLARKSVILLE (AP) — Sen. Bob Corker refuses to say whether he'll seek a third term, but he has carefully said and done all the right things to avoid provoking a spirited primary challenge next year.

The Tennessee Republican has limited public appearances back home largely to friendly civic clubs and chambers of commerce meetings, where he can regale members with tales of his pro-business agenda and blunt assessments of congressional dysfunction — all the while steering clear of direct criticism of President Donald Trump.

Until last week.

Trump's defense of white nationalists following a violent rally in Virginia that left a protester dead caused Corker to issue a blistering rebuke, raising questions about the president's stability and competence and demanding "radical changes" in the White House.

"If I'm going be a respectable public official, it had to be spoken to," Corker told Rotarians and Kiwanians a day after making those comments. "I'm an American first."

Corker's remarks last week got a smattering of applause from the crowd and put him in the vanguard of Republican lawmakers uneasy with Trump. The White House fired back Thursday, with press secretary Sarah Huckabee Sanders calling Corker's statement "a ridiculous and outrageous claim."

How it will play back in Tennessee is another question. Already there are indications that the populist wing of the Republican party in Tennessee — which includes the most ardent Trump supporters — doesn't like it one bit.

"It is time Tennessee had a senator who believes in the virtues of what makes America great and is willing to fight for it," former state Rep. Joe Carr said in a Facebook post. "We need a senator who will fight alongside President Trump not fight against him."

Like Trump's initial remarks, Carr said both sides were to blame for the violence in Charlottesville, describing the clashes as "hate on hate."

Carr's tea party-styled primary challenge of U.S. Sen. Lamar Alexander came within a surprising 9 percentage points of toppling the state's senior statesman in 2014, and he has been making noise about running against Corker next year.

Should he choose to run — and many expect he will — Corker would likely emulate the tactics of U.S. Rep. Diane Black, who went on a merciless offensive against Carr when she beat him by a 2-to-1 margin in last year's GOP House primary.

Corker is a former businessman — his construction company got its big break with a contract to install drive-thru windows at Krystal restaurants — and served as Chattanooga mayor before his election to the Senate in 2006. That campaign was tinged by its own racial undercurrent, especially when an ad produced by the Republican National Committee hit the airwaves attacking his African-American opponent, former U.S. Rep. Harold Ford Jr. of Memphis.

The ad included a white woman with blonde hair and bare shoulders looking into the camera and whispering, "Harold, call me." Critics said it made an implicit appeal to deep-seated racial fears about black men and white women. Corker called the ad tacky and said it should stop running, but it took the RNC nearly a week to pull it off the air.

Corker won that race by fewer than 3 percentage points. His advisers still insist the ad hurt the Republican more than it helped him.

Corker has since risen to the post of Senate foreign relations chairman, striking a bipartisan tone while relishing fights with former President Barack Obama. The senator reminded reporters at a stop last week that he was in the mix to become Trump's running mate and also his secretary of state. He was also photographed on a golf outing with the president and University of Tennessee football legend Peyton Manning.

"It's just an unusual relationship," Corker said. "I don't know that there's probably anybody in the United States Senate that talks to him more about issues that matter, not only to our nation but to the world. And that's a privilege.

"You know, we don't always agree, but to be in a position where you can affect outcomes like that is unusual," he said.

A moment of disagreement came earlier this summer, when Corker led the charge in the Senate on a bill to restrict the president's power to remove sanctions against Russia despite Trump's misgivings.

And on Thursday, Corker spoke out against Trump's threat to force a federal government shutdown unless Congress provides funding for a wall along the U.S.-Mexican border, saying such a move would hurt confidence in the economy.

"We need to do what we can do to solve our problems and keep government functioning the way it should," Corker said.

Larry Waters, the longtime mayor of Sevier County on the edge of the Great Smoky Mountains National Park, said Corker has performed a deft balancing act with the president.

"Folks appreciate him having a little bit of independence and being able to speak his mind and being able to say, 'I don't agree with the president 100 percent of the time — I agree with him on so many issues,'" Waters said. "But there are things that I think any rational person would say I wish he hadn't said this or done that."

Scott Cepicky, the chairman of the Maury County Republican Party, said the GOP-controlled Congress will have to start delivering in the aftermath of the failed efforts to repeal Obama's signature health care law, or it could blow back on Corker's re-election effort next year.

"If we're sitting here and we're still hashing out in 2018 about tax reform and corporate tax reform, I think he's going to have some problems," Cepicky said.