The US Justice Department will tighten its rules around obtaining records from members of Congress, Attorney General Merrick Garland said Monday, as revelations indicate that the department under former President Donald Trump had secretly seized records from Democrats and members of the media.

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

Garland’s statement came as a Justice Department official said the top national security official, John Demers, planned to leave by the end of next week. He is one of the few Trump appointees who remain in the Biden administration.

The Justice Department is struggling to contain the fallout over revelations that it had confiscated phone data from House Democrats and reporters as part of an aggressive investigation into leaks. The disclosure is also forcing Biden administration officials to wade back into a fight with their predecessors – something they’ve wished to avoid.

Demers will be replaced temporarily by Mark Lesko, the acting US attorney in the Eastern District of New York, an official said until Biden’s official pick, Matthew Olsen, is approved by the Senate.

News outlets reported last week that the Justice Department had secretly subpoenaed Cupertino, California-based Apple Inc. in 2018 for metadata from two Democratic members of the House Intelligence Committee – California Rep. Adam Schiff and California Rep. Eric Swalwell – as their committee was investigating Trump’s ties to Russia. Schiff, at the time, was the top Democrat on the panel, which was led by Republicans.

Now the House Intelligence Committee Chair, Schiff said on Monday that he had spoken with Garland, who had given his commitment to an independent investigation by the inspector general.

Some people might not know they were targeted because the Apple notification was by email and showed up in the spam filters of some of those who were contacted, the person said.

House Judiciary Committee Chair Rep. Jerry Nadler, D-N.Y., announced an investigation into the subpoenas on members of Congress and journalists. Senate Judiciary Committee Chair Sen. Dick Durbin, D-Ill., demanded a copy of the subpoena and other records about the decision to obtain the order.

Meanwhile, Senate Minority Leader Mitch McConnell, R-Ky., lambasted a demand by Democrats that former attorney generals William Barr and Jeff Sessions testify before a committee on the subpoenas, saying his Democratic colleagues had given into the “urge to pick at the scab of politically-motivated investigations.” He defended Barr, saying the move was a “witch hunt in the making.”

“There is no need for a partisan circus here in Congress,” he said.

Apple said that it couldn’t challenge the warrants because it had so little information available and that “it would have been virtually impossible for Apple to understand the intent of the desired information without digging through users’ accounts.”

The department’s inspector general has launched a probe into the matter after a request from Deputy Attorney General Lisa Monaco.

Inspector General Michael Horowitz said he would examine whether the data subpoenaed by the Justice Department and turned over by Apple followed department policy and “whether any such uses, or the investigations, were based upon improper considerations.”

In addition, Monaco has been separately tasked with “surfacing problematic matters deserving high level review,” Garland said.

Garland emphasized in his statement Monday that “political or other improper considerations must play no role in any investigative or prosecutorial decisions.”