▶ Watch Video: Trump Justice Department seized House Democrats’ data

Washington — Attorney General Merrick Garland pledged Monday he would “move swiftly” to take action in response to an investigation by the Justice Department’s inspector general into an effort by the department during the Trump administration to obtain communications data from members of Congress and congressional staff.

In a statement, Garland said there are “important questions that must be resolved in connection” with the move by the Justice Department as it sought to determine the source of leaks of classified information about aides to then-President Donald Trump and their contacts with Russia.

“I have accordingly directed that the matter be referred to the Inspector General and have full confidence that he will conduct a thorough and independent investigation,” Garland said. “If at any time as the investigation proceeds action related to the matter in question is warranted, I will not hesitate to move swiftly.”

Garland said that while the review from the Justice Department’s internal watchdog is pending, he has instructed Deputy Attorney General Lisa Monaco to “evaluate and strengthen the department’s existing policies and procedures for obtaining records of the legislative branch.”

“Consistent with our commitment to the rule of law, we must ensure that full weight is accorded to separation-of-powers concerns moving forward,” the attorney general said.

Sources confirmed to CBS News last week that federal prosecutors under the Trump administration subpoenaed Apple in 2017 and 2018 for data from the accounts of two Democrats on the House Intelligence Committee, current Chairman Adam Schiff and Congressman Eric Swalwell, both of California, as part of a probe into leaks of classified information. Records of at least a dozen people connected to the House Intelligence panel were also seized, including data from committee aides and family members, including a minor.

Both Swalwell and Schiff were among the most vocal critics of Mr. Trump during his presidency.

Microsoft was also subpoenaed in 2017 for data from a congressional staffer, the company said. The New York Times first reported the subpoenas. 

News of the requests for lawmakers’ information caused an uproar on Capitol Hill, as Democrats accused the Trump administration of abusing its power and targeting Mr. Trump’s political opponents. Senate Democratic leaders on Friday demanded Jeff Sessions and William Barr, who were attorneys general under the former president, testify before Congress about the efforts to secretly obtain the data from lawmakers’ and others.

On Sunday, Senate Majority Leader Chuck Schumer also called on John Demers, the assistant attorney general for the Justice Department’s National Security division, to testify about the seizure of lawmakers’ data. But a department spokesman confirmed to CBS News on Monday that Demers will be leaving the department on June 25.

Demers, who joined the Justice Department in February 2018, is the longest-serving political holdover from the prior administration. He did not assume his role until after the subpoenas at issue were executed and gag orders on the tech companies imposed.

The Justice Department has also come under recent criticism after it notified the New York Times, Washington Post and CNN that it had secretly obtained reporters’ phone and email records during the early months of the Trump administration as part of leak investigations. The Justice Department said last week it will no longer seize reporters’ records during such probes.