A second House Republican said Wednesday that he can't see himself supporting Donald Trump for president.

"I just don't see how I get to Donald Trump anymore," Rep. Adam Kinzinger, R-Illinois, said in an interview on CNN's "The Situation Room."

Kinzinger, who served in Iraq and Afghanistan, explained that he wanted "to get there" in supporting the GOP presidential nominee, but Trump has said and done so many things that is preventing that endorsement.

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Last month, for example, he said he went to the Republican National Convention in Cleveland on a Monday hoping that he could at least "mildly endorse" Trump by Thursday of that week. On Wednesday, however, Kinzinger said he saw Trump's comments about NATO and "decided to hold off."

Kinzinger then said that Trump's comments bashing the Khan family was the breaking point.

"Then this spat, this unbelievable spat with the family of a fallen soldier, a fallen soldier who swore to protect and defend the Constitution of the United States, wouldn't even initially say we honor the family for their service. Immediately [he] took it as what it was to him, an affront to him. Between that, blaming George W. Bush for 9/11, and all the other sins we've seen in the past, Donald Trump for me is beginning to cross a lot of red lines in the unforgivable on politics," Kinzinger explained.

Asked what he plans to do for November's general election, Kinzinger said, "I'm not going to support Hillary" and added that he could write in a candidate or even sit out the election.

He said it's a "tough position" that he's in because his district voted for Trump during the primary season. But Kinzinger argued that Trump has thrown "all these Republican principles on their head" and he has praised Russian President Vladimir Putin, made fun of disabled people and he didn't know that Russia had intervened in Ukraine.

"I'm saying for me personally, how can I support that? Because he has crossed so many red lines that a Commander in Chief, or a candidate for Commander in Chief should never cross. It's a tough position for me to be in," he said.

While Kinzinger didn't go as far, Rep. Richard Hanna, R-New York, announced Tuesday that he would not vote for Trump and instead cast a vote for Hillary Clinton, becoming the first GOP member of Congress to say he's backing her for president.