Former Vice President Mike Pence speaks to guests at the Republican Jewish Coalition Annual Leadership Meeting on November 18, 2022 in Las Vegas, Nevada.
CNN  — 

Former Vice President Mike Pence has filed a motion asking a judge to block a federal grand jury subpoena for his testimony related to January 6 on the grounds that he is protected by the Constitution’s Speech or Debate Clause, according to a source familiar with the filing.

Pence had publicly signaled that he planned to resist the subpoena, arguing it was “unconstitutional and unprecedented.” His legal team filed the motion Friday night, the same day former President Donald Trump’s attorneys asked a judge to block Pence from speaking to a grand jury about certain matters covered by executive privilege.

The Pence motion – filed as part of sealed proceedings – seeks to stop testimony pertaining to his legislative functions around January 6, which could potentially include a broad swath of testimony. It is separate from Trump’s motion, which argues that the former president can shield former aides from sharing internal communications.

Special counsel Jack Smith is seeking documents and testimony related to January 6, 2021, and wants Pence to testify about his interactions with Trump leading up to the 2020 election and the day of the attack on the US Capitol.

But the former vice president asserts that because he was also acting as president of the Senate that day, he is shielded by the Speech or Debate Clause, which protects lawmakers from certain law enforcement actions targeted at their legislative duties.

Pence has written a memoir detailing his interactions with Trump leading up to January 6, which could complicate efforts to resist the subpoena.

His team previously indicated to the Justice Department that he’d be open to answering questions if they were limited to the matters he had previously discussed publicly, including in his book, a source told CNN.

Pence’s legal team did not comment. The Justice Department also did not comment.

Since taking over the investigation into efforts to overturn the 2020 election, Smith, who has a reputation for moving quickly, has accelerated the probe’s pace and began imposing tight deadlines on subpoenas. Smith also is simultaneously investigating Trump’s handling of classified documents after leaving office.

Trump huddled with several members of his legal team at his Mar-A-Lago resort in Palm Beach last week to discuss Smith’s investigations, according to a source familiar with the meeting.

Smith recently subpoenaed Trump’s former chief of staff Mark Meadows and Trump’s former national security adviser Robert O’Brien in both of the Trump-related probes, and investigators have sat down with his former acting Department of Homeland Security Secretary Chad Wolf as part of the probe into 2020 election interference.

CNN’s Katelyn Polantz contributed to this report.