Former President Donald Trump and former Vice President Mike Pence
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 request, in a new filing submitted secretly in a sealed proceeding on Friday, comes after the Trump team had already indicated to special counsel Jack Smith, who is overseeing the Justice Department’s criminal investigations into Trump, that the former president intended to assert privilege over Pence’s testimony.

The DOJ had previously asked a judge to compel Pence’s appearance before the grand jury, CNN reported last week.

It is unclear how long it will take for the sealed proceedings to unfold, but it’s possible that the district court resolves the dispute, or that it will be appealed to a federal appeals court and perhaps, eventually, to the US Supreme Court.

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.

In the lead-up to the congressional certification vote, Pence faced enormous pressure from Trump and his allies to disrupt lawmakers’ plans to validate Joe Biden’s win. As president of the Senate, Pence was tasked with presiding over the certification proceedings.

Pence ultimately rebuffed those calls for him to disturb Congress’ plans – a decision he stands by now. But he also has announced his plans to fight the subpoena in Smith’s probe.

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.

This headline has been updated.