During an interview with a local television station in Ohio on Monday, Donald Trump doubled down on his comments about Khizr Khan, arguing that Khan—​the father of slain Army captain Humayun Khan—​spoke so passionately against Trump because he's "bothered" by Trump's immigration plan.

“[Border security] is a very big subject for me. And border security’s very big. And when you have radical Islamic terrorists probably all over the place, we’re allowing them to come in by the thousands and thousands. And I think that’s what bothered Mr. Khan more than anything else," Trump told ABC 6.

“And, you know, I’m not going to change my views on that. We have radical Islamic terrorists coming in that have to be stopped. We’re taking them in by the thousands.”

Khan, who is Muslim, has sparred publicly with Trump in the days since he delivered his fiery speech at the Democratic National Convention, where he argued that Trump's proposal to ban Muslim immigrants from entering the U.S. is unconstitutional and would prevent patriotic Muslim-Americans from serving the country. 

In the days following Khan's speech, Trump suggested that Khan's wife, Ghazala, did not speak at the convention because of the female subservience expected in some more traditional sects of Islam. 

On Sunday, Roger Stone, a former Trump adviser, tweeted that Khizr Khan is an agent of the Muslim Brotherhood who is "helping Hillary."

Trump running mate Mike Pence posted a statement to Facebook on Sunday arguing that both he and Trump believe Humayun Khan should be "cherished" by all Americans. He maintains support for Trump's proposal to "suspend immigration from countries that have been compromised by terrorism."

A spokesperson for the Trump campaign did not immediately respond to a request for comment.