Donald Trump limped into August with his campaign under fire from both Democrats and Republicans appalled by his escalating feud with the family of a fallen Muslim soldier, whose parents intensified their criticism of Trump on Monday amid statements of support from GOP leaders.

Khizr Khan and his wife Ghazala, whose son was a captain in the U.S. Army when he died serving in Iraq in 2004, have found themselves at the center of the presidential campaign ever since Khizr Khan spoke out against Trump during an emotional speech last week at the Democratic National Convention.

“This candidate amazes me,” Khizr Khan said Monday on the Today show. “His ignorance. He can get up and malign the entire nation.”

The father, who has criticized Trump’s proposal to ban Muslims from entering the U.S., renewed his call on Monday for Republican leaders to rebuke Trump and for American voters not to put him in office. “This candidate is void of empathy, so I will continue to reach out to Republican voters to refrain from voting for this candidate,” he said. “He needs to mend his way.”

Trump has struggled to put the controversy behind him, alternatively lashing out against the Khans, calling their son a “hero,” saying the issue he wants to discuss is terrorism, and criticizing the media for its coverage of his latest high-profile feud.

“This story is not about Mr. Khan, who is all over the place doing interviews, but rather RADICAL ISLAMIC TERRORISM and the U.S.,” Trump said Monday morning on Twitter. “Get smart!”

“Mr. Khan, who does not know me, viciously attacked me from the stage of the DNC and is now all over T.V. doing the same – Nice!,” Trump said in an earlier tweet.

Republican leaders like House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell have issued statements of support for the Khans, but have not wavered in backing their party’s nominee. Arizona Republican Sen. John McCain, a military veteran and former prisoner of war who Trump dismissed earlier in the campaign as only being a hero because he was captured, said in a statement Monday that “it is time for Donald Trump to set the example for our country and the future of the Republican Party.”

“While our Party has bestowed upon him the nomination,” McCain said, “it is not accompanied by unfettered license to defame those who are the best among us.

“Lastly, I’d like to say to Mr. and Mrs. Khan: thank you for immigrating to America,” McCain added. “We’re a better country because of you. And you are certainly right; your son was the best of America, and the memory of his sacrifice will make us a better nation—and he will never be forgotten.”

Khizr Khan, speaking on CNN, said Trump’s reaction to his convention speech is “proof of his ignorance and arrogance.” He told the Washington Post late Saturday that Trump’s response was “typical of a person without a soul.”

The back-and-forth between the parents and Trump has dominated the campaign. It led nearly a dozen families of fallen soldiers on Monday to demand an apology from Trump for his “repugnant remarks,” accusing the billionaire of “cheapening the sacrifice” of their deceased relatives in the way he responded to the parents of Captain Humayun S.M. Khan.

Khizr Khan told CNN on Monday that he and his wife “want to be out of this controversy.” “That is not our style. … This is not our path,” he said, adding that “there was no need” for Trump to comment further. “We want to maintain our dignity,” Khizr Khan added.

Meanwhile, Ghazala Khan shared a touching story of the last conversation she had with her son on Mother’s Day in May 2004 before he was killed after a vehicle packed with IEDs exploded near him. The nervous mother said she pleaded with her son to be safe and reminded him that he only had a short time left before he was set to return home when he called her.

“As a mother, I said please, Humayun, don’t be [a] hero. Just stay back and finish your time,” she said on CNN. “You will be home soon. Please just stay back.”

“He laughed and said, ‘Mom, you know these soldiers are my responsibility. I don’t want anything to happen to them because I am responsible. I have to do my job. I am responsible for my soldiers,” Ghazala Khan recalled. “And he came back, but he came back as a hero.”