He played the president's State of the Union claim about crime in El Paso and said, "Whatever your position on border barriers or a border wall, the case the president lays out about El Paso is simply false".
In January, O'Rourke said that walls on the border "ensure death". "If you could snap your fingers and make El Paso's border wall disappear, would you?" According to Federal Bureau of Investigation crime data, the city had the third lowest violent crime rate among 35 US cities with a population over 500,000 in 2005, 2006 and 2007 - before construction of a 57-mile-long fence started in mid-2008.
"Tonight, the President will join the millions of Americans who understand that a southern border wall is essential to border security", election campaign manager Brad Parscale said in a statement along with a video showing what it said were El Paso residents speaking of the need for walls.
Trump has failed to persuade Congress to fund his wall project, with Democrats accusing the president of using the whole issue to boost his political base, rather than fix the complex border situation.More news: BTS To Grace This Year's Grammys With Their Presence
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Trump made the claim last week in his State of the Union Address when he said El Paso "used to have extremely high rates of violent crime - one of the highest in the country, and considered one of our nation's most unsafe cities". Both sides face a Friday deadline to reach an agreement or face another possible shutdown - Trump also has threatened to declare a national emergency to address what he describes as a security crisis. Ted Cruz of Texas.
Another Texan who has already declared his candidacy for president is also criticizing Trump's rally in El Paso. The rally is being led by former Democratic congressman Beto O'Rourke, who represented the area until stepping down from Congress earlier this year and is reportedly weighing a 2020 White House bid.
But many in El Paso, site of Trump's rally Monday night, say the city was safe for decades and embodies a cross-border spirit that transcends walls rather than prove they work.
Paul Steinhauser is a politics reporter based in New Hampshire.