Transcript for Police clash with migrant caravan near border

The images of chaos south of the border, migrants pushing forward. President trump warning that if they are not stopped, he will send the U.S. Military to the border. Here's Jonathan Karl. Reporter: Police in riot gear today faced with migrants fleeing deep poverty and gang violence in Central America. The caravan of an estimated 3,000 or so people, many of them families with children, broke through a fence near Mexico's border with Guatemala. President trump says he's prepared to bring in the military to keep them out of the United States. If that doesn't work out, we're calling up the military, not the guard, we're calling up the military. And we're going to have the military stationed. They're not coming into this country. They might as well turn back. They're not coming into this country. Reporter: After declining last year, the flow of undocumented immigrants is now surging to near record levels on president trump's watch. More than 37,00 apprehended at the u.s./mexican border in August alone. Now the president wants to make the migrant caravan a defining issue for the midterm elections. This will be an election of Kavanaugh, the caravan, law and order, and common sense. Reporter: The president is on a campaign blitz, 16 days on the trail since labor day. He's telling his supporters that even though he is not on the ballot, the midterm elections are really all about him. Get out in 2018, because you're voting for me in 2018. You're voting for me. And I'm not on the ticket, but I am on the ticket. Because this is also a referendum about me. Get out and vote! I want you to vote. Pretend I'm on the ballot. Reporter: Still, the president tells the associated press that if Republicans lose, it won't be his fault. Jon, with us live from the white house. You heard the president saying this is the election of Kavanaugh and the caravan. President trump will be campaigning today and tomorrow, but there will be a lot of him in the days ahead? Reporter: He will be a near constant presence. If they stick to the current plan, he will spend more days Owen the campaign trail than he does at the white house between now and November 6th. Jon, thank you.

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