U.S. Sen. Chuck Grassley and three other key lawmakers are asking the FBI to provide all memos relating to former FBI Director James Comey's interactions with his superiors in both the Trump and Obama administrations.

Grassley, an Iowa Republican who chairs the Senate Judiciary Committee, said Wednesday that the White House was being called on to provide records of interactions with Comey, including any audio recordings. He was joined in the request by Sens. Dianne Feinstein, D-Calif., Lindsey Graham, R-S.C., and Sheldon Whitehouse, D-Rhode Island.

"As chairman of the committee of jurisdiction, I plan to exercise my constitutional responsibility of oversight, and as I have said so often, we need to get the facts out into the open," Grassley told Iowa reporters in a conference call Wednesday. "We can’t just rely on selective leaks and reports. I also expect that we have a hearing on this matter in the near future."

Later that day, the Justice Department announced it has tapped former FBI director Robert Mueller to be a special counsel overseeing the Russia investigation.

The news comes as President Trump and his administration grapple with the fallout from explosive revelations earlier this week that Comey, the fired FBI director, kept notes of a February meeting indicating Trump asked him to close the agency's investigation into former National Security Adviser Michael Flynn.

The requests followed news reports that Comey authored internal memos after meetings and conversations with President Donald Trump to document what he perceived to be improper behavior by the president with respect to ongoing investigations at the FBI, according to the New York Times' reporting. Grassley said the president implied in a tweet last week that the White House may have recordings of interactions with Comey.

In a letter to Acting FBI Director Andrew McCabe, the Senate Judiciary Committee leaders requested “all such memos, if they exist, that Mr. Comey created memorializing interactions he had with Presidents Trump and Obama, Attorneys General Sessions and Lynch, and Deputy Attorneys General Rosenstein, Boente, and Yates regarding the investigations of Trump associates’ alleged connections with Russia or the Clinton email investigation.”

A separate letter sent to White House Counsel Donald McGahn seeks “all White House records memorializing interactions with Mr. Comey relating to the FBI’s investigation of alleged ties between President Trump’s associates and Russia, or the Clinton email investigation, including all audio recordings, transcripts, notes, summaries, or memoranda.”

The Judiciary Subcommittee on Crime and Terrorism, led by Chairman Graham and Ranking Member Whitehouse, is conducting an investigation into potential Russian interference in the 2016 United States elections, Grassley said. He said committee leadership expects to hold a hearing on these matters.

In a related matter Wednesday, the Senate Intelligence Committee invited Comey to testify on reports that Trump asked him to drop an investigation into Flynn, the former national security adviser.

U.S. Sen. Joni Ernst, R-Iowa, issued a statement regarding the controversies swirling around the Trump administration: “I have a lot of questions and it is important that we learn the facts. We must take a look at the relevant documents and hear from former FBI director James Comey. As I have made clear, Russia is not our friend, and the U.S. must be extremely cautious in any engagement with them."

Grassley was asked Wednesday where he would draw the line in terms of presidential behavior becoming obstruction of justice if it's true that Comey was fired after refusing to drop an investigation.

The Iowa senator said he had heard so many lawyers offering opinions on TV in the previous 24 hours that it would be difficult to draw a conclusion. "I would say that a question that comes to my mind is that if it was going to be interference, then it seems to me that Comey should have taken action on interference," Grassley said.

Grassley said some of Trump's problems are obviously self-inflicted, but he also questioned the motivations of people reading government memos over the telephone to the New York Times. Classified information should be kept secure to protect national security, he added.

"All of this tends to detract from the work that needs to get done on health care, tax reform and job creation, deregulation and our important role that we play in international peace as a leader of the free world, particularly against ISIS," Grassley said. But Congress still has a job to do, regardless of who is president or what the president does, he commented.

Prior to the news that the Justice Department had appointed Mueller to oversee the investigation, Grassley expressed little interest in establishing an independent commission to investigate the Trump campaign's ties to Russia, or having a special prosecutor address such issues.

"Both of them would delay and delay and delay getting a final answer," Grassley said, explaining that everyone tells him, "Get this investigation over." Four committees in Congress are already at work, and the establishment of a commission would require the work to start over again.

Following the announcement of Mueller's appointment, Grassley issued a statement that said, in part, "As I’ve said many times before, the American people deserve to know how Russia attempted to meddle in our democratic process. ... I have a great deal of confidence (in) Deputy Attorney General Rosenstein and I respect his decision. Mueller has a strong reputation for independence, and comes with the right credentials for this job. At the end of the day, we need a public accounting of what went on to restore faith in government."