U.S. Customs and Border Protection announced Monday evening that U.S. Border Patrol agents "will be conducting a crowd control exercise" in El Paso on Tuesday, Election Day. El Paso is Democratic Senate candidate Rep. Beto O'Rourke's home and political base — he held his final rally there Monday night — and the "mobile field force demonstration" will start at 10 a.m. between El Paso's primarily Latino Chihuahuita neighborhood and that neighborhood's designated polling location, about half a mile away, Texas Monthly reports.

CPB spokesman Roger Maier declined to comment on the exercises but pointed to an earlier statement about preparations for the Central American migrant caravan hundreds of miles south of the U.S. border, walking north. "No walls, no CBP exercises (are) going to keep us from honoring our laws, our commitments," O'Rourke said when informed of the Border Patrol drill Monday night. "Why this is happening now, why the president is stirring these issues up at this moment with 24 hours before we decide this election, I'll leave that to you to conclude."

Other Texas Democrats were similarly confounded by the Border Patrol exercises, as was the ACLU. "The location, next to a totally Hispanic neighborhood, is suspicious," said ACLU Texas head Terri Burke. "The timing of this — Election Day — is suspicious. This administration, and by extension the (Gov. Greg) Abbott administration, have done quite enough to intimidate voters without staging military rehearsals on the day our nation exercises our most important democratic obligation: voting."

Border Patrol agents now carry semi-automatic rifles on the bridge separating El Paso and Mexico, citing the caravan. Trump's deployment of up to 15,000 troops to the border will cost $220 million, and a Pentagon risk assessment found the migrant caravan poses no risk to the U.S., CNBC reports, citing U.S. defense officials and intelligence sources. Peter Weber

Update 1:21 p.m.: This exercise was postponed Tuesday. Border Patrol did not provide additional details.