Former Vice President Mike Pence has been subpoenaed by the special counsel handling investigations into efforts by former President Donald Trump and his allies to alter the results of the 2020 election, AP reported.

The subpoena to Pence, which is a part of the investigation by special counsel Jack Smith, was served in recent days, as per AP citing a person with direct knowledge of the event.

The unusual scenario of a former vice president potentially testifying against his former boss in a criminal inquiry comes as Pence considers running for president as a Republican against Trump in 2024. Since a mob of Trump supporters stormed the United States Capitol building on Jan. 6, 2021, in an attempt to derail Democrat Joe Biden's triumph, the two have been estranged.

The subpoena is a bold move by a prosecutor who supervised the Justice Department's public corruption section for years and oversaw indictments against significant political figures. Given Pence's close proximity to Trump for four years when significant decisions were being considered and prepared, the move lays the stage for a likely executive privilege argument. It is unclear whether efforts to obtain Pence's voluntary testimony were halted before the subpoena was issued.

Pence was a key participant in Trump's efforts to maintain power after the 2020 election. Trump incorrectly claimed that his Vice President, who had a ceremonial role in monitoring election certification, could simply reject the results and return them to the crucial states he contested.

On Jan. 6, Trump supporters, fueled by the idea that the election was stolen, marched to the Capitol building, ruthlessly pushing past police and smashing out windows and doors as Pence presided over the certification of Biden's victory. As others in the mob screamed, "Hang Mike Pence!" the vice president was led to safety with his staff and family.

While the mob was in the Capitol, Trump said in a tweet: “Mike Pence didn’t have the courage to do what should have been done to protect our Country and our Constitution.”

Smith, who was appointed special counsel by Attorney General Merrick Garland in November, has been tasked with overseeing investigations into Trump's efforts to undermine his defeat, his actions leading up to the Jan. 6 insurgency at the Capitol, and his possession of top-secret government documents at his Florida estate, Mar-a-Lago.

Federal prosecutors have issued subpoenas to various state Republican party chairs in connection with a conspiracy by Trump loyalists to elevate bogus presidential electors in critical battleground states won by Biden as a means of subverting the vote.

Federal prosecutors have also questioned several Trump administration employees, including former Trump White House lawyer Pat Cipollone and Pence's own former chief of staff, Marc Short.

Election authorities in various states whose results Trump challenged have received subpoenas requesting contacts with or involving Trump and his campaign aides, indicating the scope of the inquiry.

A House committee examining the Jan. 6 incident suggested that the Justice Department file criminal charges against Trump and allies who assisted him in launching a pressure campaign to overturn his election defeat in 2020.

This comes shortly after the recent discovery of the documents in the former Vice President's residence piled on top of already ongoing investigations by the Department of Justice into classified documents in the possession of former US President Donald Trump and sitting US President Joe Biden.