Robin Vos, a Wisconsin Republican, is expected to meet with the panel on January 6.

A senior Wisconsin GOP official who said former President Donald Trump called him to urge him to overturn the 2020 state election results is scheduled to testify Wednesday with the House panel investigating the January 6 riots, said two people familiar with the matter.

Robin Vos, the speaker of the Wisconsin state Assembly, was subpoenaed by the committee this year after he publicly revealed that Trump called him 20 months after the election to demand that he throw out the results. President Joe Biden won battleground status by some 20,000 votes.

Trump called after the Wisconsin Supreme Court issued a ruling restricting the use of absentee ballot boxes in future elections. Trump tried to convince Vos that the ruling should apply retroactively, which Vos told him was not possible.

Vos’s refusal to try to throw out the election results led Trump to campaign against his re-election. Vos, who is the longest-serving speaker in Wisconsin history, ultimately prevailed in his primary, but only by 3 percentage points, the smallest margin in his political career. He recently was re-elected as speaker.

Wisconsin Democrats previously criticized Vos for allocating nearly $700,000 to investigate the results of the 2020 state election. The investigation turned up no evidence of widespread fraud, and Vos later said the election had not been stolen.

A spokesperson for the January 6 committee declined to comment on Vos’s scheduled appearance. NBC News has asked Vos for a comment.

A federal judge on Monday rejected Trump’s argument that he has “absolute immunity” in response to a lawsuit alleging he committed civil rights violations in his attempts to challenge the results of the 2020 presidential election.

The House committee has conducted a series of interviews with former Trump officials in recent weeks.

Kellyanne Conway, who was a senior adviser to Trump from the start of his term until August 2020, met with the panel for nearly five hours Monday.

On Tuesday, former White House deputy chief of staff Tony Ornato would appear for an interview before the committee, a person familiar with the panel’s plans said.

The committee is expected to publish a final report detailing the findings of its investigation soon. The panel is not expected to continue beyond January, when Republicans take control of the House.