In a ruling that remains under seal, the judge also said that Pence can still decline to answer questions related to January 6, the source said, adding that Pence can still appeal the ruling. The appeal option is being evaluated, the source said.
The source, confirming reports by CNN and NBC, said the judge's decision compels Trump's former vice president, and potential challenger for the Republican presidential nomination in 2024, to appear before the federal grand jury but shields him from testifying about January 6, 2021, itself.
Asked during an interview on Newsmax on Tuesday as to whether he would appeal the order, Pence said there was a limited amount he could say on the proceedings.
"I'm pleased that the court accepted our argument and recognized that the Constitution's provision about speech and debate does apply to the vice president," he said.
"But the way they sorted that out and the requirements of my testimony going forward are a subject of our review right now and I'll have more to say about that in the days ahead."
In February, a source told Reuters that Pence was preparing to resist a grand jury subpoena to secure his testimony.
Ahead of the January 6 events, Trump had repeatedly lambasted Pence, publicly and privately, for refusing to try to prevent Congress from certifying Biden’s win in the 2020 election, sources told Reuters at the time.
Representatives for Special Prosecutor Jack Smith, who is leading the US Department of Justice's investigation into Trump and his allies' alleged efforts to overturn his 2020 election loss, could not be immediately reached for comment.