The chairman of the Senate's homeland security committee is demanding information from the General Services Administration about why it turned over Trump transition documents to Special Counsel Robert Mueller’s team for its Russia investigation – something lawyers for the transition team have called “unlawful.”

In a Tuesday letter first obtained by Fox News, Wisconsin Sen. Ron Johnson, Republican chairman of the Committee on Homeland Securty and Government Affairs, requested a variety of information from the GSA director, including a description of the steps taken by the agency to determine if it was appropriate to provide the documents to the special counsel’s office.

Johnson also asked for the name of the GSA staff member who authorized handing the documents over to Mueller.

“GSA’s alleged actions could have serious ramifications for presidential transitions in the future,” Johnson wrote in the letter. “An incoming administration must be ready to govern on Day 1. Any threat to the close coordination between the transition and outgoing administration could create vulnerabilities to governance, readiness and national security.”

Over the weekend, Kory Langhofer, the counsel to Trump for America, said that the GSA “did not own or control the records in question,” and that the document release could violate the Fourth Amendment. That amendment protects against unreasonable searches and seizures.

Trump for America is the nonprofit organization that facilitated the transition between former President Barack Obama and President Trump.

The GSA, a government agency, provided the transition team with office space and hosted its email servers.

TRUMP TRANSITION LAWYER: MUELLER IMPROPERLY OBTAINED DOCUMENTS IN RUSSIA PROBE

In his letter to the agency, Johnson said the GSA did not have “authority” over transition documents. He said that the Presidential Transition Act of 1963 gave the GSA a prominent role in the transition process, but that it “acts merely as a facilitator of office space, supplies and services.”

“The National Archives and Records Administration considers records of the presidential transition team to be private records – not federal or presidential records," Johnson said. "GSA does not have authority over the transition’s operations, its employees or its records.”

The attorney said they discovered the “unauthorized disclosures” by the GSA on Dec. 12 and 13 and raised concerns with the special counsel’s office.

Those records included emails sent and received by 13 senior Trump transition officials. Among the officials who used transition email accounts was the former national security adviser Michael Flynn, who pleaded guilty to a count of making false statements to FBI agents in January and is now cooperating with Mueller's investigation.

“GSA’s alleged actions could have serious ramifications for presidential transitions in the future." — Wisconsin Sen. Ron Johnson, chairman of the Senate homeland security committee

The special counsel's office has said it went through the "appropriate" process to obtain the emails.

“When we have obtained emails in the course of our ongoing criminal investigation, we have secured either the account owner’s consent or appropriate criminal process,” Peter Carr, spokesman for the special counsel’s office, told Fox News.