The Republican chairmen of two Senate committees are calling on the acting director of national intelligence and Attorney General William Barr to release information regarding Obama administration officials’ “unmasking” of Michael Flynn.

Sens. Chuck Grassley and Ron Johnson sent a letter Wednesday in response to confirmation that Richard Grenell, the acting director of national intelligence, had declassified information related to the Flynn unmasking.

Grenell declassified the information after the Justice Department filed a motion last week to withdraw charges against Flynn for making false statements to the FBI.

A senior intelligence official told The Daily Caller News Foundation that Grenell declassified a list of names of Obama-era officials who requested classified information about Flynn during the presidential transition period in 2016 and 2017. The Justice Department said Tuesday that it has no plans to release the information, but that Grenell can publish the information if he chooses.

Grassley and Johnson’s letter highlights a sense of urgency among Republicans regarding the release of the unmasking documents and other information from the Trump-Russia probe.

“We wholeheartedly agree that transparency is needed now more than ever,” Grassley, chairman of the Senate Finance Committee, and Johnson, chairman the Senate Committee on Homeland Security and Government Affairs, wrote in their letter.

“One of the most significant unanswered questions about what occurred during the 2016 election is how many Americans were ‘unmasked,’ at whose request, and for what purpose.”

“We respectfully request that you make available to us, as soon as possible, all information regarding the ‘unmasking’ of U.S. persons requested by members of President Obama’s administration around the time of the 2016 election through January 2017,” they added.

The list of names declassified by Grenell last week seemingly shows who in the Obama administration made requests to unveil the name of an American in transcripts of phone calls with Sergey Kislyak, the former Russian ambassador to the U.S.

The transcript reportedly showed that Kislyak spoke with Flynn in late December 2016. Flynn would plead guilty to making false statements to the FBI in a Jan. 24, 2017 about the substance of his conversation with Kislyak.

It is not illegal for government officials to make unmasking requests. But someone in the administration may have broken laws regarding the disclosure of classified information by leaking Flynn’s involvement in the phone call with Kislyak to The Washington Post.

Columnist David Ignatius reported in a Jan. 12, 2017 column at the Post that Flynn spoke with Kisylak. Ignatius also raised the question of whether Flynn violated the Logan Act, an obscure law that prohibits private citizens from negotiating with foreign governments on U.S. national security matters.

Grassley and Johnson noted that Grenell and Barr have recently declassified a slew of documents related to the Trump-Russia probe.

Grenell declassified footnotes from the Justice Department inspector general’s report on Crossfire Hurricane which showed that the FBI received evidence of Russian disinformation in the Steele dossier.

Grenell also pressured Rep. Adam Schiff to release transcripts of interviews that the House Intelligence Committee conducted during its Russia investigation. The transcripts showed Obama administration officials said they had not seen evidence of collusion between the Trump campaign and Russia by the time they left office.