Swing-state GOP senator calls on Trump to apologize to the Khans

Sen. Ron JohnsonRonald (Ron) Harold JohnsonJuan Williams: Putin wins as GOP spins GOP senator: Harley-Davidson is right to move some production overseas GOP senator: Trump’s policies doing 'permanent damage' MORE (Wis.), who faces a tough reelection race in November, on Wednesday joined the Republicans calling on Donald TrumpDonald John TrumpTrump says he doesn't want to use 'adversary' to describe Russia Comey urges Americans to vote for Democrats in midterms Roby wins Alabama GOP runoff, overcoming blowback from Trump criticism MORE to apologize for his comments to the parents of Army Capt. Humayun Khan, a Muslim soldier who was killed in Iraq in 2004.

Johnson, considered among the most endangered incumbents as he faces former Sen. Russ Feingold (D-Wis.), had previously praised the Khans, who spoke at the Democratic National Convention last week, in a statement that made no mention of Trump.

But on Wednesday he went further in an interview with WTMJ radio, as first reported by The Associated Press, calling on the GOP presidential nominee to say he's sorry for attacking Khans.

"I’ve spoken to a number of Gold Star moms and dads, and they just deserve our utmost respect. What else can you say? I can't put myself in their position — I can't imagine losing a child. I can’t imagine that sacrifice. So all you can do is respect it and honor it and that’s all that you should do," Johnson said.

"He should apologize," he added.

Trump had slammed Khizr Khan, saying he had no right to question his views on the Constitution. He also suggested Khan's wife was not allowed to speak at the convention because of her religion.

On Tuesday, New Jersey Gov. Chris Christie, the first of the 2016 White House hopefuls to endorse Trump, said his response was "inappropriate."

And a spokeswoman for House Speaker Paul RyanPaul Davis RyanSenate Dems build huge cash edge in battlegrounds Kelly lobbied Republicans to rebuke Trump after Putin press conference: report Lobbying world MORE (R-Wis.), AshLee Strong, said that the Speaker "rejects" Trumps criticism.

"The Speaker has made clear many times that he rejects this idea, and himself has talked about how Muslim Americans have made the ultimate sacrifice for this country," she said.

Trump on Tuesday said that he did not regret his statements, including responding to Khan's questions about his sacrifices by discussing his successful business career.

"I don’t regret anything," Trump said.

"I said nice things about the son, and I feel that very strongly. But, of course, I was hit very hard from the stage, and you know it’s just one of those things — but, no, I don’t regret anything."