Bob Corker has just delivered a seriously sharp rebuke to Donald John Trump Sr.

Why is it important that such a rebuke comes from Corker?

He’s a Republican U.S. senator; he hails from Tennessee, one of the states that seceded from the Union in 1861; he is ostensibly allied with the president on most public policy issues.

The backdrop for Corker’s rebuke gives his statement plenty of gravitas.

The president weighed in on that terrible Charlottesville tragedy over the weekend. He has, in effect, taken up with the white supremacists who provoked the riot that killed a young woman who was among the counter protesters who battled with hate groups that were protesting the taking down of a statue of Confederate Gen. Robert E. Lee.

The nation is being swallowed up by the controversy that has ensued. Democrats, understandably, have been outraged by Trump’s remarks. Many Republicans have spoken out against racial or religious intolerance. Few of them in Congress have singled out the president and ascribed specific blame to him for inflaming the nation’s emotions in the wake of the Charlottesville tragedy.

Corker, though, has laid it out there.

“The President has not yet been able to demonstrate the stability nor some of the competence that he needs to be successful,” Corker said in Chattanooga, Tenn.

Welcome aboard, Sen. Corker. Many millions of Americans have been saying those very things — and a lot more — about the president. Many of us even said so while he was campaigning for the presidency. A few folks predicted he would govern like a maniac.

Count me as one who now believes that Trump is worse than I feared he would be. I was hoping he might be able to grow into the job of president.

Corker did use the phrase “not yet been able” when discussing Trump’s performance. The word “yet” suggests Corker believes — or hopes — the president will figure it out. I have little faith of that occurring.

Still, Sen. Corker’s rebuke is strong. It also is important.