FIRST ON FOX: Rep. August Pfluger, R-Texas, introduced legislation on Friday that would require the Department of Homeland Security to reveal the number of known or suspected terrorists who have attempted to enter the United States -- a number the Biden administration has so far refused to reveal.

The legislation would require DHS to publish the number of individuals who attempted to enter the U.S. and who are on the Terrorist Screening Database (TSDB). That database contains the information of those "known or reasonably suspected of being involved in terrorist activities."

HOUSE HOMELAND REPUBLICANS PUSH DHS ON WHY NUMBER OF MIGRANTS ON TERROR DATABASE IS NOT MADE PUBLIC 

It would require the government to publish a monthly update on the number of encounters on a monthly basis, the geographic regions where the encounters occurred, and how those encounters took place.

"We’ve heard Secretary Mayorkas says the border is secure, so if that is true what I want to know is: What is there to hide when you’re talking about people who are on the terror watchlist that have entered this country?" Pfluger said.

Republicans have been pushing for months to get the administration to reveal that number, but the Biden administration has declined, saying it is law enforcement sensitive (LES).

Pfluger, the lead Republican on the House Homeland Security Intelligence and Counterterrorism subcommittee, told Fox that law enforcement officials had told him that the LES designation is only for when there is an ongoing investigation.

"And if there's not an ongoing investigation, and releasing numbers or some details will not impede future or ongoing investigations, then there’s no reason to keep it sensitive," he told Fox News in an interview. 

BORDER PATROL OFFICIAL'S TWEET ON CAPTURE OF ‘POTENTIAL TERRORIST’ DELETED; CBP SAYS IT VIOLATED PROTOCOL

Former Border Patrol Chief Rodney Scott has repeatedly sounded the alarm over the number of TSDBs coming across the border, telling fellow agents that it was "at a level we have never seen before. "

"We have terrorist threats we can’t get into in this type of a forum but they are real," he told Fox News’ Bret Baier in October.

In March, Fox News reported that at least four migrants whose names match those on the terror watch list had been picked up by U.S. Border Patrol since the beginning of the fiscal year -- but that number has likely risen since then.

In December a tweet by a top Border Patrol official identifying a "potential terrorist" captured at the U.S.-Mexico border was deleted, with Customs and Border Protection (CBP) saying it was deleted because it contained "law enforcement sensitive information" and violated protocols.

Republicans on the House Homeland Security, including Pfluger, wrote to DHS Secretary Alejandro Mayorkas in November, pushing for DHS to reveal the number -- and have argued that they are not looking for more sensitive information such as identities to be released. 

They suggested in that letter that the administration was not revealing the number for political purposes, in the context of a border crisis that has seen a massive spike in apprehensions and "gotaways" at the border. 

"It’s obviously derogatory on their performance," Pfluger told Fox. "We have the worst border crisis we've ever experienced, there's more drugs, fentanyl, there’s crime and trafficking, every single community is a border community, every state is a border state." 

"So if they release this number, and I suspect it would be much higher than previous years…then it would be another failing grade on their performance in keeping the country safe," he said.

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The bill comes as there are growing questions as to how the British-born suspect in the Texas synagogue hostage standoff was able to enter the U.S. despite a lengthy criminal history and reports of extremist behavior -- although British media has reported that British intelligence dropped an investigation into the suspect, and he was not on a watch list.

Republicans in the House and Senate are calling for briefings from DHS and FBI to reveal information pertaining to that case, and how the suspect -- Malik Faisal Akram -- was able to get into the U.S.