Sen. Bob Corker: Trump Is 'Going to Have to Change' “I think that he’s going to have to change," Corker said on "This Week."

 -- Senate Foreign Relations Committee Chairman Bob Corker has a recommendation for Donald Trump’s campaign: It’s time to shift from primary mode to the general election matchup.

The Tennessee senator, who appeared on ABC News’ “This Week” on Sunday, said the likely Republican presidential nominee would have to begin to adjust his tone as he moves toward the 2016 GOP convention unopposed.

“They’ve moved beyond the primary process this week to move to the World Series of this election,” Sen. Corker told George Stephanopoulos. “I think that he’s going to have to change. I’m not talking about him necessarily changing his views, but I think that he’s moving into a different phase, he’s talking to the right people.”

Corker said he was glad that Trump was talking to Republican foreign policy leaders like Former Secretaries of State James Baker and Henry Kissinger, and that his overall worldview represents a shift toward Baker's “selective engagement” that would be a break with the Obama and Bush administrations on foreign policy.

While Corker said he believes in Trump’s ability to be a potential “disruptor” in Washington and has even seen in the candidate “a degree of maturity stepping in,” he appeared hard-pressed to name any specific foreign policy ideas that give him confidence in Trump’s commander-in-chief abilities.

When asked whether he would help facilitate Trump’s proposal to temporarily ban Muslim immigrants, Corker said, as he has before, “I would not support it.”

He also offered a much more nuanced critique of the Trans-Pacific Partnership (TPP) trade deal with Asian nations that Trump has panned, saying it was “strategically for our nation important to get right.” Corker has previously voiced support for the passage of the massive trade deal.

Corker did say he found common ground with Trump on the issue of building a wall on the United States-Mexico border and added that whether Mexico will foot the bill, “is something that Congress will certainly debate.”

Underscoring the differences between Trump and many of his top backers in Congress, Corker also said that he does not “condone” Trump’s comments about U.S. District Judge Gonzalo Curiel being unfit to hear a case against Trump University because of his Mexican heritage.

But that was all Corker would say on the issue.

“We can press on to another topic,” he said.