This unusual presidential campaign year now includes testy exchanges between a fallen soldier's family and Republican nominee Donald Trump. Back-and-forth volleys began when Khizr Khan, who came from Pakistan in 1980, endorsed Hillary Clinton on national TV during the Democratic National Convention's last night. Standing alongside his wife Ghazala, Khan said: "Donald Trump consistently smears the character of Muslims." He wondered if Trump had ever read the U.S. Constitution. “I will gladly lend you my copy," Khan said theatrically while holding a pamphlet version (see video below). "In this document, look for the words 'liberty' and 'equal protection of law.'" Khan also spoke about his son – U.S. Army Capt. Humayun Khan, a 27-year-old Muslim-American soldier killed in Iraq in 2004 by a suicide bomber. "If it was up to Donald Trump, [my son] never would have been in America," Khan stated, adding that the political newcomer had "sacrificed nothing and no one."

In an ABC interview July 31, three days after the six-minute convention remarks, Trump wondered why Ghazala Khan stood silently on stage in Cleveland and speculated that she might not have been allowed to speak. "I'd like to hear his wife say something,” he told a newspaper columnist earlier. (Ghazala later said she was too emotional to speak.) Four days after the convention, Trump tweeted that Khazir Khan "viciously attacked me" and "is all over the place doing interviews." In a statement, the Republican candidate commented: "While I feel deeply for the loss of his son, Mr. Khan, who has never met me, has no right to stand in front of millions of people and claim I have never read the Constitution, (which is false) and say many other inaccurate things."

Critics of Trump, including some Republicans, said he should show respect to the parents of a serviceman who earned a Bronze Star and Purple Heart. "He's a man of sadistic cruelty. With him there's no bottom," tweeted Peter Wehner, a presidential speechwriter during George W. Bush terms last decade. A New York Times editorial calls the nominee's remarks "deplorable and mystifying," adding: "Why would a presidential candidate mock the parents of a soldier who died in combat?" As a sidelight, the controversy kindled interest in the pocket-size Constitution booklet waved on TV. The American Civil Liberties Union mailed 100,000 free copies to people who asked, and a $1 version on Amazon’s site became an instant best-seller.

Fallen soldier's dad says: "Trump is totally devoid of any decency." -- Khizr Khan

Trump says: "I've made a lot of sacrifices. I've worked very, very hard. I've created thousands and thousands of jobs." – Response on ABC to Khan’s rebuke

Journalist says: "His continued feud with the family of a fallen Muslim soldier may be the most ill advised and foolhardy folly in recent political memory." – Charles Blow, New York Times columnist