A flame that was lit last week in Philadelphia continued to scorch Republican presidential candidate Donald Trump on Monday, over his criticism of a bereaved Muslim family whose son, an Army captain, was killed in Iraq.

Members of nearly two dozen Gold Star families - those who have had a loved one die in military service to the United States - signed a letter demanding an apology and calling Trump's remarks "repugnant and personally offensive to us."

The new president of the Veterans of Foreign Wars, the nation's oldest and largest veterans group, called Trump's attack "out of bounds," and said it "will not tolerate anyone berating a Gold Star family member for exercising his or her right of speech or expression."

Arizona Sen. John McCain, the 2008 Republican presidential nominee and a former Vietnam War POW, rebuked Trump and said that nomination does not carry "unfettered license to defame those who are the best among us."

At Independence Mall, Sarah Assad took Trump's comments about the Khan family personally. The 26-year-old Muslim American said she often finds herself justifying her religious beliefs to others during this election cycle.

"Trump's comments were an insult to a family that has sacrificed so much for this country," the New York paralegal said. "They are Muslim immigrants who lost a son in war, and it is they who stand for true American beliefs, not Trump."

The Khan family provided the most dramatic moment of the Democratic National Convention, taking the stage Thursday at the Wells Fargo Center to oppose Trump's plan to ban Muslims from entering the country, saying it was unconstitutional.

Khizr Khan, the father of Capt. Humayun Khan, accused Trump of never having read the Constitution, dramatically pulling a pocket version from his suit jacket and saying to Trump, "I will gladly lend you my copy."

As his wife, Ghazala, stood beside him, Khan said of the Republican nominee, "You have sacrificed nothing."

The couple immigrated to the U.S. from the United Arab Emirates when their son was 2. Capt. Khan was 27 when a vehicle packed with explosives approached his compound in Iraq in 2004. He instructed his men to seek cover as he ran toward it, the Washington Post reported. The car exploded, killing him instantly. He was awarded the Bronze Star posthumously.

In response to critics, Trump has suggested that Ghazala Khan was forbidden to speak at the convention because she is a Muslim woman, and questioned whether her husband's words were his own.

"Who wrote that? Did Hillary's scriptwriters write it?" Trump asked in an ABC News interview.

Over the weekend, the billionaire real estate developer said he had made "a lot of sacrifices" in building businesses that employ thousands of people.

On Monday, Trump tweeted that he had been "viciously attacked" by Khan.

"This story is not about Mr. Khan, who is all over the place doing interviews, but rather RADICAL ISLAMIC TERRORISM and the U.S. Get smart!"

If there was a beneficiary of the controversy, it might be the Constitution itself - with the 1789 document suddenly receiving new attention.

The Constitution leaped onto Amazon.com's bestseller list after Khan's speech. And visits to the interactive online Constitution operated by the National Constitution Center were up 16 percent since the speech, a representative said.

The nonpartisan center gave out 22,000 pocket copies of the Constitution to delegates and visitors at the Democratic and Republican conventions, and continues to provide each visitor to the center with a foldout, wallet-size copy.

The center's president and CEO, Jeffrey Rosen, keeps a copy of the Constitution in his pocket, often pulling it out to frame a discussion or simply review its language when people are arguing over one point or another.

"It's striking and inspiring to see how simply seeing a physical copy of the Constitution has inspired a national debate about its centrality," Rosen said Monday by phone. "And it's exciting to see that in these divided times, it's the one thing that people can gather around."

At another Philadelphia landmark, Joan Brookes, 62, from Philadelphia, said her visit to the Liberty Bell reminded her of the American values of liberty and freedom, which she said Trump rejected with his comments toward the Khan family. Trump's response to the parents of a war hero went too far, even for him, she said.

"As a country, we are on the precipice of either embracing true liberty or rejecting everything that America stands for and going back to the 1950s with Trump," Brookes said.

Juanita Cortes, 21, a student at Temple University, criticized Trump's understanding of the Constitution. His policies that call for a ban on Muslim immigrants, she said, are explicitly in contrast to the First Amendment.

Cortes said she has read through the Constitution and knows the Bill of Rights by memory - as it is part of her job as a summer tour guide on the Big Double Decker Bus. She described his comments towards the Khan family as "un-American."

"Trump has crossed all boundaries when he insults the parents of an American war hero," she said.

Criticism of Trump's comments streamed in Monday from both sides of the aisle.

Republican congressional candidate Brian Fitzpatrick, running in a Bucks County-based swing district, said: "Capt. Khan is an American hero and any attempt to imply otherwise is both patently false and offensive. . . . I vehemently reject Mr. Trump's statements on this matter and call on him to apologize."

Sen. Pat Toomey (R., Pa.), fighting for reelection in one of the nation's most closely watched Senate races, said the Khan family, like all Americans who lose loved ones in the defense of the country, "deserve our gratitude and honor. Anything else is inappropriate."

His Democratic rival, Katie McGinty, called Toomey's words "meaningless if he's still working to put Donald Trump in the White House."

Charlie Dent, a Republican congressman from the Lehigh Valley, weighed in as well: "U.S. Army Capt. Humayun Khan is a hero by every possible definition - a soldier who put his troops first and who died while trying to protect them . . . the very definition of what it means to be an American.

"Any attempt to diminish or minimize the sacrifice that Capt. Khan, or his family, have made for our nation should be strongly condemned," Dent's statement read.

And an avowed Trump supporter ("because the alternative would be worse") in New Jersey's congressional delegation said the party's nominee needed to say he was sorry.

Republican Tom MacArthur, whose district includes parts of Burlington and Ocean Counties, said Trump "should have apologized and moved on."

Trump had his defenders as well Monday. Jack Posobiec, 31, of West Philadelphia, blamed Khan for the dispute, saying the immigration lawyer had politicized his son's death to avoid the financial hit his practice might take under a Trump presidency.

"He's trying to make a quick buck off his son's death," said Posobiec, a Navy veteran and reservist. "I've had a lot of brothers and sisters who have passed away as well. I don't see how any of that should be tied to politics."

But receptionist Fabiola Castellanos, 26, a Mexican woman who became a U.S. citizen in 2015 and lives in Willow Grove, said she thought Trump's words were partly fueled by bigotry.

"To him," she said, "it's like, 'Everyone who looks different than me or speaks different than me is below me.' "

Castellanos, a mother, also defended Ghazala Khan's decision not to speak during the convention about the son she had lost.

"If that were to happen to me," Castellanos said, "I can imagine I might not want to talk about it."

jgammage@phillynews.com

215-854-4906@JeffGammage

Staff writer Jonathan Tamari contributed to this article, which also includes information from Inquirer wire services.