Fox News poll on Wednesday showed Donald Trump behind by ten points. Amazingly the single incident most responsible is his attack on the parents of an heroic American Muslim soldier. 67 per cent of Americans, a huge majority these days, disagred with the attack. It seems likely to be Trump's Joe McCarthy moment when the rabid communist hunter was asked "Have you no shame"?

It appears not in Trump's case . It takes a special kind of nerve to attack the mother and father of a fallen United States soldier, but Donald Trump has it.

The bigoted scorn he directed at the parents of U.S. Army Captain Humayun Khan last week crossed a line I didn’t think anyone would ever willingly cross in American public life.

Khan’s parents spoke at the Democratic convention last Thursday where they informed Trump that their son, a decorated war hero, had died to protect the democratic principles that Trump’s campaign is busy tearing up. He sacrificed his life, they reminded him. Have some respect at long last.

But Trump replied by suggesting that Khan’s mother had not “been allowed” to speak about her son. Why had Ghazala Khan stood by quietly as her husband Khizr Khan talked at the convention, he asked?

In response to this question a letter signed by the bipartisan Gold Star families group – the term employed for those who have lost loved ones in military service – called Trump's comments “repugnant, and personally offensive.”

“When you question a mother's pain, by implying that her religion, not her grief, kept her from addressing an arena of people, you are attacking us. When you say your job building buildings is akin to our sacrifice, you are attacking our sacrifice,” the group wrote.

Trump, who avoided the active service draft through a bone spur complaint, had clearly been deeply rankled by Khizr Khan’s claim that his targeting of Muslims undermines the United States Constitution, and that in his own life Trump has "sacrificed nothing and no one" to protect its principles.

"I will gladly lend you my copy,” Khizr Khan said, holding up the Constitution. “In this document, look for the words, look for the words, liberty and equal protection (under) law.”

The Khans had good reason for their ire. Trump has called for a “total and complete shut down” of Muslims entering the United States, and he has also suggested a comprehensive database or registry of those already in the country be undertaken.

White House Deputy National Security Adviser Ben Rhodes lamented Trump’s incendiary plan, saying, “The fact of the matter is ISIL wants to frame this as a war between the United States and Islam. And if we look like we're applying religious tests on who comes into this country, we're sending a message that essentially we're embracing that frame. And that is going to make it very difficult to partner with Muslim communities here in the United States and around the world to prevent this scourge of radicalization that we need to be focused on.

“We should be making it harder for ISIL to portray this as a war between the United States and Islam, not easier,” he added, using an acronym for ISIS, or the Islamic State.

Trump, as usual, was unbowed by all the fierce criticism, claiming he had made many personal sacrifices in his own life that the Khan family knew nothing about.

By the weekend his decision to compare his sacrifices to the Khans had blown up Twitter with the mocking hashtag, #TrumpSacrifice.

#trumpsacrifice He sacrificed his 1st wife for his 2nd wife. Then sacrificed the 2nd wife for the 3rd. Then sacrificed 3rd wife at RNC.

— Jim Sumstine (@CopyJim) August 1, 2016

Posters claimed Trump had probably made impressive sacrifices like flying commercial, taking the subway once, playing golf on a public course or staying at a four-star hotel.

He went with gold seatbelts instead of platinum on his Trump jet. #TrumpSacrifice

— Josh Axelberd (@JoshAxelberd) July 30, 2016

But amid all the push and pull of campaigning it's important to remember that the Khans’ son was a distinguished U.S. Army captain, instantly killed by a car bomb in 2004 while guarding his base in Iraq. His personal sacrifice saved the lives of dozens of his fellow soldiers and civilians. He was posthumously awarded a Bronze Star and Purple Heart. He stood up against ISIL and he gave his life to defeat it.

"I once had an opportunity to talk about myself, but I didn't." #TrumpSacrifice

— MightyAni (@MightyAni) July 30, 2016

Brian Duffy, chief of one of the nation's most prominent veterans groups the Veterans of Foreign Wars, blasted Trump: “There are certain sacrosanct subjects that no amount of wordsmithing can repair once crossed. Giving one's life to [one's] nation is the greatest sacrifice, followed closely by all Gold Star families, who have a right to make their voices heard.”

Trump's statements have so regularly enraged his own party that it's past time for them to set up a special press office to disavow each thing he says as contradicting the core principles of the Republican Party.

Former presidential candidate, Senator Lindsey Graham of South Carolina, was incandescent. “Unacceptable doesn't even begin to describe it,” he said. “This is going to a place where we've never gone before, to push back against the families of the fallen.

“There used to be some things that were sacred in American politics – that you don't do – like criticizing the parents of a fallen soldier even if they criticize you.”

But in Trump's America, as he often says himself, all gloves are off.

In Trump's America, as he often says himself, the gloves are off.