Sen. John McCain may have been in a tough political fight with Barack Obama in 2008 but that didn't prevent him from showing what a real mensch he is by putting down a supporter who claimed the Democratic candidate was an Arab. 

The Arizona senator quickly and clearly told her it wasn't so.  "No, ma'am. He's a decent family man [and] citizen that I just happen to have disagreements with on fundamental issues and that's what this campaign's all about. He's not [an Arab]."

Given a similar question and similar opportunity, Trump blew it. 

A man wearing a Trump T-shirt at a New Hampshire rally told the GOP frontrunner, "We have a problem in this country: it's called Muslims. We know our current president is one. You know he's not even American."

Trump merely nodded.

The man went on to say, “We have training camps growing where they want to kill us. That’s my question. When can we get rid of it?”

Trump, an outspoken birther who has spent years claiming Obama was not born in the United States and is not qualified to be president, didn't disagree. Maybe intentionally.  Maybe he saw it as affirmation of his own attacks on the president.

Instead, he said, "We’re going to be looking at that and plenty of other things.”

A day later a spokesman said Trump didn't hear the question but the replay on U-Tube and elsewhere showed that was unlikely.  She said he was response only referred to the part about training camps. 

It is troubling that the frontrunner not only fails to confront such bigotry but that he actually encourages it.

Trump has been running a nativist campaign. He famously launched his presidential bid by calling Mexican immigrants criminals, rapists and drug dealers. Like the rest of the GOP field, he has been staunchly anti-immigration.

Hillary Clinton quickly tweeted a response: "Donald Trump not denouncing false statements about POTUS & hateful rhetoric about Muslims is disturbing, & just plain wrong. Cut it out. –H"