Trucks at Otay Mesa crossing
Trucks wait in a long queue for border customs control to cross into the U.S. at the Otay Mesa border crossing. REUTERS/Jorge Duenes

White House aides said Sunday that President Trump is serious about his threat to close the border if Mexico does not stop immigrants from Central America.

“It certainly isn’t a bluff. You can take the president seriously,” said White House counselor Kellyanne Conway on “Fox News Sunday.”

She said the United States has “never seen a surge” in immigration like the current one and called on Congress to change asylum laws.

Acting White House chief of staff Mick Mulvaney told ABC’s “This Week” that it would take “something dramatic” for Trump not to shut down the border.

Last week Kevin McAleenan, the commissioner of Customs and Border Protection, said immigration enforcement has reached a breaking point.

In recent days Trump has repeatedly threatened to close either the entire border or sections of it. No specifics have been released, but any closure could affect the nearly $2 billion in daily trade, with trucks held at the border and daily workers prevented from crossing.

“The Democrats are allowing a ridiculous asylum system and major loopholes to remain as a mainstay of our immigration system. Mexico is likewise doing NOTHING, a very bad combination for our Country. Homeland Security is being sooo very nice, but not for long!” tweeted Trump on Sunday night.

The threats come as the San Diego Regional Chamber of Commerce’s 14th annual bi-national economic delegation to Mexico City began Sunday. More than 90 business, community and government leaders from San Diego and Baja are taking part in the trip, including San Diego Mayor Kevin Faulconer.

Chris Jennewein is founder and senior editor of Times of San Diego.