CNN —Former President Donald Trump has asked a federal court to block former Vice President Mike Pence from speaking to a grand jury about certain matters covered by executive privilege as part of the criminal investigation into efforts to overturn Trump’s 2020 election loss, sources familiar with the move told CNN. The DOJ had previously asked a judge to compel Pence’s appearance before the grand jury, CNN reported last week. Since taking over the DOJ investigation into efforts to overturn the 2020 election, Smith, who has a reputation for moving quickly, has accelerated the probe’s pace. The grand jury subpoena that has been issued to Pence seeks documents and testimony related to the events of January 6, 2021, when the US Capitol was attacked by pro-Trump rioters as Congress prepared to certify the 2020 election results. The former vice president asserts that because he was also acting as president of the Senate that day, he is shielded by the Constitution’s Speech or Debate Clause, which protects lawmakers from certain law enforcement actions targeted at their legislative conduct.