Story highlights McCain sharply criticized Trump for his remarks about the Khans

The controversy has been raging since Khan spoke at the DNC

(CNN) After delivering a passionate speech about the Constitution at the Democratic National Convention last week, Khizr Khan, the father of a Muslim-American soldier killed in Iraq in 2004, has spent the several days defending himself and his wife from attacks by Donald Trump.

Now he's also defending Republicans who have sparred with the GOP presidential nominee, particularly Arizona Sen. John McCain, who Khan says was a source of encouragement for him during his son's deployment. Khan's son, the late Army Capt. Humayun Khan, was killed by suicide bombers 12 years ago. But before Humayun was killed, his father sent him McCain's book, Why Courage Matters: The Way to a Braver Life.

"Senator McCain -- he's my hero," Khan told CNN in an interview . "The last book my son read that I sent him was Senator McCain's book about courage: "Why Courage Matters." So for me to hear Donald Trump malign my hero -- my son's hero -- it is just mind-boggling."

Trump first criticized McCain last summer during a town hall in Iowa when he questioned whether McCain, a Vietnam War pilot who spent several years undergoing torture as a prisoner of war after his plane was shot down, should really be considered a hero.

"He's not a war hero," Trump said. "He was a war hero because he was captured. I like people who weren't captured."

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