FIRST ON FOX: Republican lawmakers, led by Sen. Roger Marshall, R-Kansas, on Thursday wrote to DHS Secretary Alejandro Mayorkas quizzing him about the extent to which he may have used a personal email address for personal business -- after a fiery exchange earlier this year, in which the DHS chief called the claims "false."

The senators wrote to Mayorkas seeking more information about the use of private email for work-related matters, which Marshall first raised as an issue in April during Mayorkas’ testimony before the Senate Homeland Security Committee after a Freedom of Information Act disclosure. They are seeking information about failures to comply with DHS rules on records, any additional communications and steps taken to create a "culture of careful communications and strict compliance with all federal laws."

Lawmakers on the letter include Sen. Mike Lee, R-Utah., Mike Braun, R-Ind., J.D. Vance, R-Ohio, Ted Cruz, R-Texas, and James Lankford, R-Okla.

Mayorkas was asked about his use of private email by Marshall in the hearing in April and said "Your assertion is false, senator."

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Mayorkas testifies

U.S. Homeland Security Secretary Alejandro Mayorkas testifies before a House Appropriations Subcommittee on April 27, 2022 in Washington, DC.  (Kevin Dietsch/Getty Images)

"If somebody errantly sends me an email on my personal email that should have been sent to my work email, I forward it to my work email -- that’s what I do. I fulfill my responsibility scrupulously and I have 100% confidence in the integrity of my actions," he said.

The Americans for Prosperity Freedom of Information Act lawsuit led to the disclosure of hundreds of pages of emails and texts from Mayorkas’ personal email and cellphone. In many of those messages, Mayorkas does appear to forward the message to his work email and/or informs the person to work through official channels.

"Thank you. I will review as soon as I can. I will forward this to my work e-mail. Please use my work e-mail," he says in one.

 However, there were significant redactions to the release, with dozens of full pages redacted before the release -- something the lawmakers call "alarming."

"DHS withheld 56 pages in full and redacted over 200 others because they were ostensibly too sensitive to release," the senators say.

"As you are no doubt aware, DHS policy on the use of non-DHS email directs that ‘employees may not use non-DHS e-mail accounts to create or send e-mail records that constitute DHS records’ unless there is an ‘emergency,’ the letter says.

Instead, they say that DHS officials "intentionally communicated with you through your private account, including in instances where there were no obvious exigent circumstances justifying deviation from required agency practice" they write. "This suggests that DHS higher-level management tolerates a culture of careless communication, which skirts the spirit, if not the letter, of federal records management laws."

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Sen. Roger Marshall, who visited the border earlier this year, is leading the letter to Mayorkas.

Sen. Roger Marshall, who visited the border earlier this year, is leading the letter to Mayorkas. (Sen. Roger Marshall's office)

The Republicans argue that the volume of communications raises "serious concerns about whether all official messages sent to or from these devices were properly forwarded back to your official DHS accounts." 

In a statement to Fox News Digital, a DHS spokesperson said that Mayorkas "uses his official email and devices for official communication." 

"If someone mistakenly contacts him via his personal email about official business, the Secretary follows DHS policy and forwards it to his official account, so that the record is properly maintained and the communication continues through official channels. The Department takes FOIA, communication security and document preservation seriously, which is why this information was properly maintained and accessible," the spokesperson said.

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The letter is the latest indicator of Republican pressure on the DHS chief, who Republicans have grilled repeatedly -- particularly on his handling of the ongoing crisis at the southern border.

Fox News Digital reported on Wednesday that Mayorkas will appear before the House Judiciary Committee later this month, where he is expected to face questions on issues including immigration, border security and the efforts targeting alleged disinformation.