A number of Republican establishment senators say they plan to back GOP front-running antithesis Donald Trump if he ends up clinching the nomination. Count John McCain in despite the fact that he had his war hero status called into question by the real estate mogul earlier this year.

"It's hard to predict because a lot of things happen between now and then, but I certainly would support the nominee, no matter who it is," said McCain, a senator from Arizona and the 2008 Republican nominee, reported The Hill.

Trump mocked McCain's Vietnam war record and imprisonment over the summer, saying he was only considered a war hero "because he was captured," as HNGN previously reported. "I like people who weren't captured," Trump said, drawing widespread criticism.

Trump also said on Twitter that McCain "should be defeated in the primaries. Graduated last in his class at Annapolis--dummy!"

Iowa Republican Sen. Chuck Grassley, who chairs the Senate Judiciary Committee, also said he would support whoever gets the nomination.

"I can't see myself saying a Democratic candidate would be better for the country," he said.

Sen. Rob Portman of Ohio said he too intends to back Trump if he is nominated. "I intend to," he told The Hill. "I guess you could come up with some scenario where something crazy could happen, but I think the country's in trouble and I think if we don't have new leadership and new policies, it's hard to imagine it getting back on track."

Sen. Lamar Alexander of Tennessee said he has always supported the GOP nominee, but left a bit of wiggle room, adding, "that's as far as I'm going on presidential politics," according to The Hill.

No senators have officially endorsed the billionaire businessman, though Alabama Republican Sen. Jeff Sessions recently appeared at a Trump rally wearing one of the candidate's signature "Make American Great Again" hats. Sessions has also met with Trump to discuss his immigration and trade policies, notes Newsmax.

The senate's head, Majority Leader Mitch McConnell of Kentucky, however, has already endorsed the libertarian-minded Sen. Rand Paul, also from Kentucky.

One Senate Republican aide said most senators are holding off on endorsements until the 17-candidate field thins out. "Trump will start getting more endorsements as we get deeper into the process. It's so volatile that people are sitting on the sidelines," the aide said, according to Newsmax.

RealClearPolitics' average of polling data shows Trump leading the GOP field with 30.4 percent, followed by retired neurosurgeon Ben Carson with 16.8 percent and former Florida Gov. Jeb Bush with 8.2 percent.

Democratic front-runner Hillary Clinton leads Trump by a small margin in an average of polls going back to mid-August, though the gap has closed significantly.