Former White House Staff Secretary Rob Porter is being called to testify before the House Judiciary Committee as the panel pursues what its chairman calls an investigation into whether to draft articles of impeachment against President Donald Trump.

Porter was called to testify on Sept. 17, the same day that Trump's former campaign manager, Corey Lewandowski, and former White House Deputy Chief of Staff Rick Dearborn already have been subpoenaed to appear.

"Rob Porter was prominently featured in the special counsel's description of President Trump's efforts to obstruct justice by directing then-White House Counsel Don McGahn to fire the special counsel, and then ordering him to lie about it," Judiciary Chairman Jerrold Nadler, a New York Democrat, said in a statement Monday.

"The committee intends to hold hearings and obtain testimony over the coming months as part of its efforts to hold the president accountable as we move forward with our investigation into obstruction, corruption and abuse of power by Trump and his associates," Nadler said. "This will help the committee determine whether to recommend articles of impeachment against the president or other Article 1 remedies."

The White House declined comment on the committee's subpoena to Porter, who resigned his administration post last year amid allegations of abuse against his two ex-wives.

The subpoenas to Porter, Lewandowski and Dearborn came as congressional investigations of Trump have been stymied by the White House's refusal to let some current and former officials testify.

Lewandowski, who never served in the Trump administration, has said the committee didn't have to subpoena him. He told Fox News Radio this month that he would be happy to testify "because I want to explain that there was no collusion, there was no obstruction."