The U.S. relies heavily on immigrant labor, and if President Trump’s policies aren't reversed, the U.S. may find itself “begging for immigrants” in the future, 2020 Democratic presidential candidate Julian Castro argued Tuesday.

"Several of the industries in this country benefit already from their labor," Castro told MSNBC. "We need a young and vibrant workforce. And if we're not careful, if we don't get this right, in 20 or 30 years this nation is going to be begging for immigrants to come to this country."

Castro argued further that illegal immigration should be treated as a civil, rather than criminal matter.

“The truth is, immigrants seeking refuge in our country aren’t a threat to national security. Migration shouldn’t be a criminal justice issue. It’s time to end this draconian policy and return to treating immigration as a civil -- not a criminal -- issue,” he said.

TRUMP STANDS BY BORDER CLOSURE THREAT, AS AIDES SAY ALL OPTIONS BEING EXPLORED

Castro, 44, one of a crowded field of Democrats seeking the party's 2020 presidential nomination, has made immigration central to his platform. In a proposal published on Medium, he vowed to reverse the travel ban on migration from certain countries, cuts in refugee numbers and what he calls “wasteful spending on a pointless wall.”

Castro was the youngest member of former President Barack Obama's Cabinet, serving as secretary of Housing and Urban Development from 2014 to 2017. He previously served as mayor of San Antonio, Texas.

Castro's twin brother is U.S. Rep. Joaquin Castro, a Democrat who represents Texas's 20th Congressional District.

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Julian Castro is likely to return to the topic of immigration later this month when he is scheduled to hold a rally in his hometown of San Antonio at the same time Trump is expected to appear in Texas for fundraising events.

Fox News' Adam Shaw and the Associated Press contributed to this report.