Special counsel Jack Smith is pushing to question an attorney for former President Donald Trump about an alleged phone call the two held as investigators were building evidence about Trump’s potential obstruction of the government’s efforts to retrieve classified materials that he had retained after leaving the White House, sources familiar with the matter tell ABC News.

Smith in recent weeks has pressed for a federal judge in Washington, DC, to pierce attorney-client privilege and force Trump attorney Evan Corcoran to testify, according to those sources, about a June 24, 2022, phone call that investigators believe Corcoran held with Trump.

The alleged call would have been on the same day that investigators subpoenaed the Trump Organization for surveillance footage from Trump’s Mar-a-Lago resort as the government grew suspicious that Trump continued to hold onto classified materials even after one of his attorneys asserted in a sworn statement that he had complied with a subpoena requesting any remaining documents in his possession.

It’s not immediately clear how Smith’s investigators learned from the call, or why they have zeroed in on it as part of their investigation into potential obstruction by Trump and his legal team.

Investigators have also sought to compel the testimony of another attorney for the former president, Jennifer Little, who has also sought to assert attorney-client privilege, as part of the investigation into the Mar-a-Lago documents, sources tell ABC News. Little has been representing Trump in the Fulton County, Georgia, probe into efforts by Trump and his allies to overturn the results of the 2020 presidential election in that state. She did not immediately respond to ABC News’ request for comment.

A spokesperson for the special counsel declined to comment when contacted by ABC News. An attorney for Corcoran did not respond to a request for comment.

“President Trump has done nothing wrong,” a spokesperson for Trump told ABC News in a statement. “Radical Democrats continue to weaponize the justice system against President Trump, including in their attempts to demolish our Constitution by stripping away President Trump’s right to counsel, because they know that he will win back the White House, as he leads both Republicans and Democrats by wide margins. President Trump will not be deterred and will always continue to fight for the American people.”

Trump has blasted the DOJ’s documents probe as being politically motivated, calling it “an assault on a political opponent at a level never seen before in our Country.”

In a previous appearance before a DC grand jury, Corcoran declined to answer any questions regarding communications he had with Trump as his attorney, sources told ABC News.

Sources said that Corcoran also declined to answer questions regarding his efforts to locate potentially classified documents at Trump’s Mar-a-Lago resort following a May subpoena sent by the government for any documents that remained in Trump’s possession, as well as Corcoran’s role in drafting a document signed on June 3 by another Trump attorney, Christina Bobb, asserting that to the best of her knowledge a “diligent search” of the premises had been conducted and that all documents in response to the subpoena had been handed over.

Corcoran asserted attorney-client privilege at his testimony as a basis for declining to answer questions about whether Trump or any others in his office were aware of Bobb’s certification, or the reasons for any edits made to the certification document, sources said.

After the government built evidence through witnesses and other means following that signed statement, the FBI conducted a court-authorized search of Mar-a-Lago on Aug. 8, 2022, according to public court records. During the search, investigators found roughly 100 documents with classification markings — including some in Trump’s personal office and in a closet in his residence.

Prosecutors are trying to convince a judge to compel Corcoran’s testimony under the “crime-fraud exception,” which allows attorney-client privilege to be pierced in cases where there is sufficient evidence that legal services have been rendered in furtherance of a crime.

According to public court records, during a June 2022 visit by DOJ officials to Mar-a-Lago, Corcoran handed over 38 documents with classification markings inside a sealed envelope that he said had boxes found during a review of held inside a storage room at the estate. Corcoran told investigators he “had been advised” that all Trump’s remaining records from the White House remained in that storage room, but Corcoran restricted them from reviewing any of the boxes.

According to sources, after the August search the government found at least 76 of the roughly 100 classified documents inside that same storage room, leading investigators to believe some had been transferred there after the FBI’s search of the property.