WASHINGTON (AP) — A federal judge has ruled that former Vice President Mike Pence will have to testify before a grand jury in the Justice Department’s investigation into efforts by former President Donald Trump and his allies to overturn the results of the 2020 election.

That’s according to two people familiar with the ruling, who spoke on condition of anonymity because it remains under seal.

The people said, however, that Pence would not have to answer questions about his actions on Jan. 6, 2021, when a mob of Trump’s supporters violently stormed the building as Pence was presiding over a joint session of Congress to certify the vote.

Pence and his attorneys had cited constitutional grounds in challenging the subpoena. They argued that, because he was serving in his capacity as president of the Senate that day, he was protected from being forced to testify under the Constitution’s “speech or debate” clause, which is intended to protect members of Congress from questioning about official legislative acts.

Pence’s team is evaluating whether it will appeal.

The sealed ruling from U.S. District Judge James “Jeb” Boasberg sets up the unprecedented scenario of a former vice president being compelled to give potentially damaging testimony against the president he once served. And it comes as Pence has been inching closer to announcing a run for the 2024 Republican presidential nomination, which would put him in direct competition with his former boss.

Pence was subpoenaed earlier this year to appear before the grand jury in Washington investigating election interference.

A Justice Department special counsel, Jack Smith, is investigating attempts by Trump and his allies to overturn the results of the 2020 presidential election to keep Trump in power.

Multiple Trump aides have already appeared before the grand jury, as well as another panel examining Trump’s potential mishandling of classified documents at his Mar-a-Lago club.

A spokesman for the special counsel’s office declined to comment.

Pence has spoken extensively about Trump’s pressure campaign urging him to reject President Joe Biden’s victory in the days leading up to Jan. 6, including in his book, “So Help Me God.” Pence, as vice president, had a ceremonial role overseeing the counting of the Electoral College vote, but did not have the power to impact the results.

Pence has said that Trump endangered his family and everyone else who was at the Capitol that day and said history will hold him “accountable.”

Colvin reported from New York.