MICHEL MARTIN, HOST:

Hillary Clinton is wrapping up what's called a barnstorming tour this evening. She and her running mate Virginia Senator Tim Kaine took buses through the Rust Belt this weekend trying to sell their economic message and their team to blue-collar voters in a couple of key states. And yet, much of the political conversation this weekend is about the Khan family and Donald Trump. NPR's Tamara Keith is following the Clinton campaign on the bus tour this evening, and she's with us now. She's actually on the bus. Hi, Tam.

TAMARA KEITH, BYLINE: Hi. I am definitely on a moving bus right now (laughter).

MARTIN: So the back and forth between Donald Trump and the Khan family - we heard about this at the top of the program, but for listeners who maybe didn't hear that, could you give us a quick sketch?

KEITH: There was this powerful moment at the convention where Mr. Khan pulled out his pocket Constitution and offered it to Donald Trump. Trump was asked about this in an interview on ABC's "This Week," and he questioned whether that speech had been written by the Clinton campaign, which Mr. Khan said it was not. He questioned why Mrs. Khan didn't speak. She had in another interview said, well, actually I didn't speak because I was way too emotional. Just seeing her son's picture causes her to be upset, even all these years after he was killed in Iraq.

Then Donald Trump tweeted out this morning, quote, "I was viciously attacked by Mr. Khan at the Democratic convention. Am I not allowed to respond? Hillary voted for the Iraq War not me." Now, Hillary Clinton has also weighed in. She held a quick media availability at a place called Grandpa's Cheesebarn along the bus route here. And she was very critical of Trump, said this comes in a long line of other people or groups of people that Donald Trump has criticized.

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HILLARY CLINTON: Any one of those things is so offensive. And then to launch an attack as he did on Captain Khan's mother, a gold star mother, who stood there on that stage with her husband honoring the sacrifice of their son and who has in the days since spoken out about the overwhelming emotion that any mother would feel as her son was being honored and then to have Trump do what he did - I don't know where the bounds are. I don't know where the bottom is.

MARTIN: Tam, talk a little bit about where you've been over the last couple of days. Where did this campaign take the bus tour and what is the message that they're trying to sell there?

KEITH: The bus tour went through Donald Trump country, essentially. It went to parts of Pennsylvania and Ohio with a large population of white working-class voters, which is exactly the voters that Donald Trump has appealed to in this campaign. And what the Clinton campaign is doing by going to those places is essentially saying that they are not at this point willing to cede those votes to Donald Trump.

They believe that if people can hear their message that it will break through and that they could perhaps win those voters back. I did talk to one man at an event in Youngstown, Ohio, last night. He supports Clinton but he said a lot of his friends don't, that they're so angry about economic conditions and factory closures and other things that happened years ago that he doesn't think that they will listen to Clinton, that there's very little she could say to break through.

MARTIN: Did the upcoming presidential debates come up as well over the course of those couple of days?

KEITH: Yes. Donald Trump has tweeted out that he's concerned about a conflict between the NFL football schedule and the presidential debate schedule. We asked Hillary Clinton about that today. She said that the debate schedule was set long ago by a nonpartisan commission, and she has every intention of attending those debates.

MARTIN: That's NPR's Tamara Keith on the bus with the Clinton campaign currently in Ohio. Tam, thanks so much.

KEITH: You're welcome so much. Transcript provided by NPR, Copyright NPR.