While GOP Sen. Rob PortmanRobert (Rob) Jones PortmanOn The Money: Trump to seek new round of tax cuts after midterms | Mnuchin meets with Saudi crown prince | Trump threatens to cut foreign aid over caravan On The Money: Mnuchin to attend anti-terror meeting in Saudi Arabia | Treasury releases guidance on 'opportunity zone' program | Maxine Waters gets company in new GOP line of attack Election Countdown: O'Rourke brings in massive M haul | Deal on judges lets senators return to the trail | Hurricane puts Florida candidates in the spotlight | Adelson spending big to save GOP in midterms MORE of Ohio announced he had a “change of heart” about the issue of same-sex marriage, Sen. John McCainJohn Sidney McCainTrump: 'You know what I am? I'm a nationalist' Graham on Saudi Arabia: 'I feel completely betrayed' Meghan McCain calls Russian attacks against her father the 'highest compliment' to her family MORE (R-Ariz.) said he doesn’t see himself following suit.

Portman on Thursday became the first sitting Republican senator, and one of the highest-profile members of the GOP, to support same-sex marriages. The shift happened, he said, after his son, Will, came out to him as gay.

On Friday, McCain told CNN's Anderson Cooper that he wouldn’t be changing his mind, as the issue is at odds with his beliefs.

“I respect anyone else's decision and we all learn in life and grow and mature. I have changed my position on other issues in my life, but on this one, I had not contemplated changing my position,” he said.

McCain, who is known for breaking with the ranks of his own party, remains in line with most Republicans. Recent polls show that, at most, about 31 percent of Republican voters support same-sex marriage.

Other members of McCain’s family, his daughter, Meghan, and wife, Cindy, have made public statements urging the Republican Party to move in the same direction as the rest of the country. Meghan joined the leadership committee of the Young Conservatives for the Freedom to Marry last November, a group working to build support for gay marriage among a younger generation of conservatives.

“I look forward to spreading the message that the tenets of family, personal freedom, and responsibility point the way toward a GOP that fully embraces the freedom to marry,” she said in a statement.

Her father, though, says he is unlikely to be swayed by the views of his family, although he respects his daughter’s opinions.

“We have discussions about the issue. And she makes strong arguments and I think we ought to continue this dialogue throughout the country,” McCain said.

“And by the way,” he told Cooper, who is gay, “I have admired your forward position and stand on this issue.”