Transcript for Trump threatens to close US southern border

At that rally in Montana we mentioned last night the president also taking on the battle over the border as a caravan of thousands of migrants heads to the U.S. And the debate front and center ahead of the midterm elections and Mary Bruce has more. Reporter: Good morning. Well, the president continues to be on this midterm campaign blitz and he's hammering the issue of immigration. While questions about how to tackle this challenge are sparking testy exchanges here in the west wing. At that rally in Montana, president trump incensed about the rising level of border crossings. It's going to be an election of the caravan, you know what I'm talking about. Reporter: Trump whipping up supporters as a caravan of migrants from Honduras make their way to the U.S. It's my problem. I caused it because I have created such an incredible economy, I have created so many jobs, I've made this country with you so great that everybody wants to come in. So they're all pouring in or trying to. Reporter: Back at the white house the issue reached a boiling point Thursday sparking an explosive shouting match between chief of staff John Kelly and national security adviser John Bolton. The two men cursing at each other outside the oval office. In a statement press secretary Sarah Sanders says while we are passionate about solving the issue of illegal immigration we are not angry at one another. The administration's frustrated their policies have not discouraged migrants from flowing into the U.S. A record number of families have been apprehended at border crossings up nearly 40% this summer. With the midterm elections just two weeks ago trump made clear he thinks immigration excites his base and is good politics tweeting great midterm issue for Republicans. Now, he's ramping up the rhetoric. I'm willing to send the military to defend our southern border if necessary all because of the illegal immigration onslaught brought by the Democrats. Reporter: Threatening to close our southern border if Mexico doesn't do more. Mexico's sending planes of police to intercept the caravan. Now that fight between the president's two top aides was apparently so heated that it's renewed rumors of a possible white house departure but sources tell us neither Bolton nor Kelly have any plans to resign, at least not over this fight, Michael. We'll see how it plays out. Thank you very much. Now to breaking news in that

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