FIRST ON FOX: Sen. Ted Cruz, R-Texas, on Wednesday wrote to DHS Secretary Alejandro Mayorkas seeking more information about the screening of migrants who have come through the border via the CBP One app and are seeking to board flights.

"While Americans must present an acceptable form of identification to fly, or at least have their identities confirmed, TSA is permitting illegal aliens without ID to opt for an alternate identity verification process utilizing the…'CBP One' app," Cruz says in the letter to Mayorkas, saying the process "takes illegal aliens at their word" on certain data and allows them to obtain DHS documents and fly out of airports.

"In effect, TSA is applying one standard for verifying the identities of American citizens, and another, weaker standard for ‘verifying’ the identities of illegal aliens. This is alarming."

The U.S. has been allowing around 1,600 migrants a day to be paroled into the U.S. through ports of entry using the CBP One app, which allows migrants to upload photographs and other information and schedule an appointment.

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Cruz, the ranking member of the Senate Commerce Committee, says that even if they do not have a passport or other way to prove their identity, they can still be paroled into the U.S. 

He then says that if they try to fly out of an airport, "TSA may use his unverified name and date of birth in CBP One to verify his identity, even though the person may in fact be a terrorist or other criminal traveling under a fake identity." Similarly, he says, ICE can use that data to issue a card to them under their name and date of birth. 

While officials have stressed the biometric and biographical vetting that takes place for migrants at the southern border, both those entering legally via ports of entry through parole and those encountered entering illegally between the ports, conservatives have raised questions about the ability to verify those identities if they have few or no documents.

"When TSA later uses CBP One data to verify an illegal alien’s identity at an airport security checkpoint, the agency is merely comparing a live photograph or live answers to what the alien provided or told Border Patrol at the port of entry," Cruz says. "They are not reviewing authenticated identity documents from an alien’s home country."

Cruz also notes that while verification for migrants is free, Americans have to pay for governmental IDs at DMVs or the State Department. 

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He is seeking documents and information relating to the use of "acceptable alternate identification" by TSA, the "special circumstances" under which alternative ID can be used, and what happens to migrants without those forms of ID. He also wants to know the "disparate cost burden" on American citizens related to illegal immigrants, and how many passengers screened by TSA on Nov. 26 went through an alternate identity verification process.

It’s the latest concern raised by Republicans over migrants, both illegal immigrants and those paroled, getting on aircraft potentially with limited ID. Last year, TSA Administrator David Pekoske was grilled at a Senate hearing about a policy that allows illegal immigrants to use warrants – which represent civil immigration enforcement and are not criminal arrest warrants, as an alternative form of identification.

He told lawmakers that "under 1,000" had been allowed to travel after presenting a warrant or deportation notice to TSA.

TSA had previously said that, in the case of those who do not have acceptable forms of ID, TSA can accept certain DHS-issued forms, which are then validated via an alien identification number (A-number) and in turn checked against CBP databases, including the CBP One mobile application and TSA’s National Transportation Vetting Center (NTVC).

Pekoske said the presentation of a warrant marked the beginning of a further verification process.

"These individuals who have these arrest warrants, these arrest warrants were issued by Border Patrol or a customs officer, and they serve as a beginning of our identity verification process, so you can't walk up to a checkpoint, wave that form and then go right through into screening," he said.

Fox News Digital has reached out to DHS for comment on Cruz's letter.