FIRST ON FOX: Sen. Ron Johnson, R-Wis., is calling for answers to a slew of questions regarding the Biden administration’s handling of the crisis at the southern border and the release of migrants into the interior — as Republican pressure grows on the administration and the crisis rolls into its second year.

Johnson, who sits on the Senate Homeland Security Committee and is the ranking member of the subcommittee on investigations, followed up on previous requests for information from the Department of Homeland Security on the crisis with a letter with additional requests.

MORE THAN 47,000 MIGRANTS RELEASED INTO US BY BIDEN ADMIN IN 2021 FAILED TO REPORT TO ICE

There were 178,840 migrant apprehensions at the border in December, after a FY 2021 that saw approximately 1.7 million encounters, overwhelming border authorities, after Trump-era policies were rolled back in favor of a growing practice of releasing migrants into the U.S. interior. 

It has led to intense Republican criticism about the purported failure of the Biden administration’s focus on "root causes" in Central America, with lawmakers pointing to the rapid rollback of Trump-era policies combined with a reduced interior enforcement and a push for mass amnesty for illegal immigrants already here.

Fox News recently reported on how single adults are being released into the interior just hours after arriving in the United States, and how a smaller percentage of migrants are being removed via the Trump-era Title 42 public health policy

Jan. 23, 2022: Fox News footage shows migrants being released into the US.

While the Biden administration was forced by court order to re-implement the Migrant Protection Protocols (MPP) – the Trump-era policy that quickly returns migrants to Mexico – so far only a few hundred migrants have been enrolled in it.

Johnson’s letter requests numbers about how many migrants were released into the interior without being detained, how many were released prior to the resolution of their immigration case, and the number returned to their home country.

BIDEN'S BORDER CRISIS GOES GLOBAL WITH MORE APPREHENSIONS FROM FARAWAY COUNTRIES

The letter also zeroes in on the practice of releasing migrants with a Notice to Report (NTR) -- which was used by Border Patrol at the height of the crisis to more quickly process migrants into the interior than issuing them with a Notice to Appear (NTA). Issuing a NTA involves giving migrants a time and date for their immigration hearing and can take hours. The NTR process, which tells migrants to check in with their local Immigration and Customs Enforcement (ICE) office, allows migrants to be processed into the interior in as little as 15 minutes.

In a letter to Johnson last month, DHS disclosed that out of 104,171 Notices to Report issued to migrants between the end of March and the end of August, 47,705 failed to report within the 60-day time frame.

An additional 6,607 had not checked in with ICE and were still within the 60-day period, while 49,859 did check in within the 60-day period. DHS also revealed that between March 21 and Dec. 5, ICE issued 50,683 NTAs to migrants who had initially been released with an NTR. 

In his letter this week, Johnson requested the NTA numbers for the whole 2021 calendar year, as well as the number apprehended by ICE, the numbers deported for not checking in with ICE, the number paroled after checking in pursuant to an NTR, and the number of those placed in alternatives to detention (ATD).

The Wisconsin lawmaker also requested the numbers of known or suspected "gotaways" — migrants who successfully got past Border Patrol, and the number of aliens with criminal records who were released or paroled into the U.S. interior.

CLICK HERE TO GET THE FOX NEWS APP

Johnson and a number of other senators will be holding a press conference on the border crisis on Wednesday.

Republicans have been calling for greater transparency from the administration on everything from the number of suspected terrorists encountered at the border to the practices related to how migrants are released into the interior. That pressure is likely to build if the crisis continues in 2022, ahead of what is already likely to be a difficult midterm election for congressional Democrats.

Fox News' Bill Melugin contributed to this report.