After an event in his home state, the Tennessee Republican said Trump has not shown the "stability" or competence to be "successful." He noted that the country needs to see Trump succeed.
"I do think there need to be some radical changes," Corker told reporters, according to a video posted by a reporter for Nooga.com. "The president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful ... And we need for him to be successful. Our nation needs for him to be successful."
Republican criticism of Trump has mounted since the car attack by a suspected white nationalist in Charlottesville, Virginia, killed one person and injured many others. Trump appeared to suggest a moral equivalence between the white nationalists at the rally and protesters demonstrating against them.
Even after a handful of CEOs abandoned Trump's business councils to rebuke his response, prompting him to abruptly dissolve the advisory boards, the president on Thursday fueled the divisive debate. He tweeted against removing the "beautiful" Confederate statues and monuments.
"[Trump] also recently has not demonstrated that he understands the character of this nation," Corker said Thursday. "He has not demonstrated that he understands what has made this nation great and what it is today. And he's got to demonstrate the characteristics of a president who understands that."
"Without the things that I just mentioned happening our nation is going to go through great peril," he said.
Corker added that "helping inspire divisions because it generates support from your political base" will not help the country.
Corker is the chairman of the Senate Foreign Relations Committee. Trump reportedly considered him for secretary of state before choosing Rex Tillerson for the job.