EXCLUSIVE: Republicans on the House Oversight Committee are calling on their Democratic colleagues to provide more details about a series of trips taken to Mexico while staff were touring border detention facilities, amid reports that at least one Democrat has been involved in “coaching” migrants there on how to exploit U.S. immigration law.

In a letter to Chairman Elijah Cummings, D-Md., obtained by Fox News, ranking member Jim Jordan, R-Ohio, said there were at least two committee staff trips into Mexico in August — one of which required Border Patrol agents to provide a special escort back into the U.S.

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“Although you have the authority to direct Committee staff to travel internationally on official committee business, you have not explained why you authorized this travel into Mexico or what you sought to learn through these trips,” Jordan wrote, adding that Republicans were not notified of the trips.

Jordan went on to accuse Democrats of seeking “to delegitimize the administration’s border security efforts and vilify the men and women who protect our border.” He said GOP members are concerned the trips “could continue to result in misleading information about the administration’s border security efforts.”

Fox News has reached out to Cummings' office for a response to Republicans' claims.

Specifically, Jordan highlighted a report that said Rep. Veronica Escobar, D-Texas, was in attendance on one trip to Tijuana on Aug. 21. Escobar, who is not on the Oversight Committee, has been a vocal advocate of left-wing policies on illegal immigration.

According to The Washington Examiner, staff from Escobar’s office recently coached migrants in Ciudad Juarez on how to exploit federal immigration law — including telling would-be border crossers to pretend they cannot speak Spanish to exploit a loophole that would let them enter the U.S.

Escobar responded by calling the article “fabricated” and “fueled by xenophobia and misinformation.”

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In the letter, Jordan asked Democrats a number of questions including what the purpose of the visit was, which individuals and groups they interacted with, why Escobar’s office was invited, and what “coaching” on immigration laws, if any, was given to migrants.

The letter marks the latest controversy over Democrats’ trips to the border. Fox News first reported last month that the Department of Homeland Security had barred staffers from the committee from visiting Customs and Border Protection facilities at the U.S.-Mexico border during a trip after staff were allegedly disruptive and refused to follow instructions.

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Sources told Fox News that DHS revoked access to CBP facilities for one visit, citing staff behavior that “interfered” with law enforcement operations — including refusing to leave one site after their scheduled window, skipping some tours and being "rude" to officers.

Democrats suggested the visit was nixed due to concerns about what staff were learning from detainees about conditions on the ground. Cummings later wrote that his staff was blocked "after previous staff inspections revealed potentially serious ongoing problems with the treatment of children and adults in DHS custody."