Cipollone, Philbin expected to appear Friday before federal grand jury probing Jan. 6: Sources

Two former top Trump White House lawyers are expected to appear Friday before a federal grand jury investigating the events surrounding Jan. 6, sources familiar with the matter tell ABC News.

Former White House counsel Pat Cipollone and former deputy White House counsel Pat Philbin were subpoenaed by a federal grand jury investigating the Jan. 6 attack on the U.S. Capitol and efforts to overturn the 2020 election, ABC News reported last month.

The move to subpoena the two men has signaled an even more dramatic escalation in the Justice Department's investigation into the Jan. 6 attack than previously known. Members of former Vice President Mike Pence's staff have also appeared before a grand jury.

Officials with the Department of Justice declined to comment when reached by ABC News. A representative for Cipollone and Philbin also declined to comment.

Sources previously told ABC News that attorneys for Cipollone and Philbin were expected to engage in negotiations around any grand jury appearance, while weighing concerns regarding potential claims of executive privilege.

MORE: Ex-White House counsel subpoenaed by federal grand jury investigating Jan. 6 attack

In July, Cipollone spoke to the House Jan. 6 select committee for a lengthy closed-door interview, portions of which have been shown during two of the committee's most recent public hearings.

Cipollone spoke to the committee on a number of topics, including how he wanted then-President Donald Trump to do more to quell the riot on the day of the attack, and how Cabinet secretaries contemplated convening a meeting to discuss Trump's decision-making in the wake of the attack.

Both Cipollone and Philbin have also sat for interviews with the FBI regarding Trump's handling of documents.

Cipollone, Philbin expected to appear Friday before federal grand jury probing Jan. 6: Sources originally appeared on abcnews.go.com