WASHINGTON (AP) — House Judiciary Chairman Jerrold Nadler filed a petition in federal court Friday to obtain secret grand jury material underlying former special counsel Robert Mueller's report.

The panel is also expected to file a lawsuit next week to try to enforce a subpoena against former White House counsel Donald McGahn, a key Mueller witness, if he doesn't comply before then. That suit is expected to challenge the White House's claim that former White House employees have "absolute immunity" from testifying before Congress.

The move comes after Mueller's testimony Wednesday to Congress...