WATCH: McCain stammers when asked if he trusts Trump with US nuclear arsenal
John McCain (Photo: Gage Skidmore/Flickr)

Arizona Senator John McCain is facing some real heat about his endorsement of Donald Trump back in his home state this week.

Via the Washington Post, McCain was asked by a reporter on Wednesday if he trusted Donald Trump to have the temperament and the judgement to have the ability to launch nuclear strikes.

McCain visibly stammered and then declined to answer directly.

"Anyone that the people of this country choose to be the commander in chief and the President of the United States — therefore can lead this country, and will lead in a responsible fashion," McCain said. "Anyone who is elected president fairly in this country. And that’s the way that our democratic system works.  That’s how our government works. The American people select the next president of the United States, knowing full well what the role of the commander in chief is. Therefore, I have the utmost respect for the verdict of the people."

What's notable here is that McCain never actually says that he'd be comfortable with Trump's finger on the button -- he simply says that anyone who gets elected fairly will be fit to have control over the country's nuclear arsenal.

This wasn't the only heat the McCain took for his Trump endorsement either, a group of veterans in tandem with advocacy group is pressuring him into rescinding it.

The Huffington Post's Jennifer Bendery brings us word that a group of veterans on Thursday went to McCain's office in Arizona to deliver boxes filled with a total of 100,000 petitions urging him to un-endorse Trump:

While dropping off the boxes of petitions, one veteran told a McCain staffer that he wanted the senator to rescind his endorsement because "Trump is a bigot."

McCain is now in a very heated primary battle, but he has so far stuck with his endorsement of Trump despite the fact that the candidate has attacked him personally multiple times.

Among other things, Trump mocked McCain for getting captured while serving in Vietnam and also said that he'd done a "terrible" job of looking after veterans earlier this week.

Check out the video of McCain talking about Trump and the nuclear arsenal below.