The special counsel investigating Donald Trump’s efforts to overturn the 2020 election issued a motion to compel testimony from Mike Pence in recent days – after the Trump legal team sought to block his appearance on executive privilege grounds, sources familiar with the matter said.

The compulsion motion against Pence marks a pre-emptive move by the special counsel to rebut the executive privilege arguments before Pence had even made an appearance before the federal grand jury in Washington DC pursuant to a subpoena issued last month, the sources said.

While Pence has suggested he would contest the subpoena, the Guardian has previously reported that is understood to involve him at least appearing before the grand jury and asserting the so-called speech or debate protection for congressional officials to specific questions.

The Trump special counsel Jack Smith, however, appears to have issued the motion to compel – earlier reported by CBS News – not in response to Pence’s expected actions, but in response to a recent executive privilege motion filed in the case by Trump’s legal team seeking to stop Pence testifying in the investigation.

Trump’s legal team has reflexively filed executive privilege motions to stop multiple top former Trump White House officials from testifying in the criminal investigation into the January 6 Capitol attack.

That has led to protracted litigation with federal prosecutors before the chief US judge in the District of Columbia, Beryl Howell. The executive privilege fight with Pence’s chief of staff Marc Short took at least four months – that is thought to have delayed parts of the investigation.

Howell, who has generally ruled in favor of the government on executive privilege disputes, even if they do take months to resolve, is slated to step down on 16 March. She will be replaced as the chief judge by James Boasberg, who previously oversaw the secret foreign surveillance court.

The Pence subpoena is more complicated than other legal battles over executive privilege because there are two privilege assertions at play: Pence’s own expected speech or debate assertions, as well as the standard executive privilege fight by the Trump legal team as intervenors in the case.

Whether the special counsel filed the motion to compel in response to the Trump legal team, in order to deal with the privilege issues sequentially – executive privilege is also generally a weaker protection than the speech or debate clause – was not clear, and a spokesman did not respond to a request for comment.