Three House committee chairmen delivered a final warning Friday to Homeland Security Secretary Alejandro Mayorkas, telling him to turn over details about terrorism suspects who’ve sneaked across the southern border or else they’ll seek to issue a subpoena to force him to comply.

They said they’ve been seeking the data for more than four months and “to date, you have failed to comply satisfactorily with our requests.”

“If the Department continues to fail to produce the requested documents by October 13, 2023, we will consider other measures, including use of the compulsory process, to gain compliance and obtain this material,” wrote Rep. James Comer, chairman of the Oversight and Accountability Committee; Rep. Jim Jordan, chairman of the Judiciary Committee; and Rep. Mark Green, chairman of the Homeland Security Committee.

That compulsory process is a subpoena.

The Washington Times has contacted Homeland Security for this story.

Republicans have been troubled by the surging number of terrorism suspects detected at the southern border since President Biden took office.

According to public data from Customs and Border Protection, 151 people whose identities matched the government’s terrorism screening data set have been nabbed by Border Patrol agents along the southern border this fiscal year. That is in addition to 98 last year and 15 in fiscal year 2021.

By contrast, just 11 were detected during the Trump administration from 2017 to 2020.

Security experts worry about who isn’t being detected amid the record flow of illegal immigrants now breaching the border or so-called “gotaways.”

CBP used to refuse to report the TSDS numbers, calling them sensitive law enforcement information. The agency reversed course in the spring of 2022 under pressure from House Republicans.

Being on the terrorism watchlist doesn’t automatically mean one is a terrorist, but it does indicate a government agency has reason to suspect ties to terrorists.

Mr. Mayorkas has said when agents encounter terrorism suspects, they are denied entry or detained as security risks and, unless they win their immigration cases, are deported.

The GOP chairmen say they want to verify Mr. Mayorkas’ claims.

They asked for the immigration files of all of the migrants who did flag in the TSDS, including whether they were detained and deported. The chairmen also asked for the department’s estimate of security risks within the gotaway population.

In the letter to Mr. Mayorkas, the chairmen said their repeated prods for the data have been met with weak excuses about “interagency equities” or “sensitive” information.

On Sept. 11, the department responded with a two-page letter pointing to already public information and offering a classified briefing “to address these questions.”

That, the chairmen said, “is unacceptable.”

“Our initial letter sought specific and easily identifiable records that the Department should be able to readily produce. We are unaware of any ‘past precedent’ referenced in the Department’s response, and the Department has cited none,” the chairmen wrote.

They added: “While the Committees are open to receiving briefings on national security matters in a classified setting, such a briefing is not a substitute for the documents and information we seek.”

• Stephen Dinan can be reached at sdinan@washingtontimes.com.