(CHICAGO) One Republican Illinois congressman says he won’t be supporting his party’s presidential nominee. US Rep Adam Kinzinger said Wednesday he won’t be supporting Donald Trump in November.

In an interview with CNN, Kinzinger said Trump was ‘beginning to cross a lot of red lines of the unforgivable in politics.’

He cited Trump’s comments that the November election will already be rigged in Hillary Clinton’s favor, saying that it’s ‘unheard of’ for a candidate to question ‘our ability to do votes here.’

The final straw for Kinzinger, though, came when Trump attacked the family of Army Captain Humayun Khan, who criticized him at the Democratic convention. Kinzinger ripped into Trump for taking their comments as “an affront to him.”

It’s a change of heart for the Congressman, who just two weeks ago at the RNC, said he’d “keep open the possibility of backing Trump.”