(CNN) The House Judiciary Committee is subpoenaing former White House staff secretary Rob Porter, the Democratic-led panel announced Monday.
Porter's subpoena is the sixth issued to officials close to the President in the wake of the release of the Mueller report by Chairman Jerry Nadler, a New York Democrat, and his committee as part of its investigation into President Donald Trump and possible obstruction of justice. The committee has been authorized to issue subpoenas to 17 individuals in total. The committee is asking Porter to testify on September 17.
"As I've said before, any other American would have been prosecuted based on the evidence Special Counsel Mueller uncovered in his report. 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," Nadler said in a statement.
So far, McGahn has refused to comply with his congressional subpoena because the White House asserted that he has absolute immunity from testifying before Congress. The committee has filed a lawsuit to force him to testify.
Two other officials have testified but did not answer nearly any questions about events after the 2016 election at the direction of the White House.
McGahn's assistant Annie Donaldson, whose notes made for some of the more interesting reading in the Mueller report, answered written questions and is expected to testify in November.
Former White House communications director Hope Hicks testified behind closed doors in June. According to the transcripts, Hicks would not discuss conversations she had with the President while at the White House. Former Trump campaign manager Corey Lewandowski and former deputy chief of staff Rick Dearborn were both subpoenaed earlier this month.
Lewandoski, the first non-White House employee to be subpoenaed by Nadler, said he would be willing to testify about his campaign role but not about conversations with the President since he took office.
Porter's testimony could be critical in trying to establish the mindset of the President as he strategized what to do about the Mueller investigation while it was underway.
Porter, who was known to take contemporaneous notes, is among the most cited sources after McGahn in the second volume of the Mueller report, the part that covers obstruction as opposed to possible collusion.
A former chief of staff of Utah Republican and former Sen. Orrin Hatch, Porter is a former Rhodes scholar and a lawyer who clerked on the DC circuit of appeals, The 41-year-old was the only Trump White House senior staff member who can lay claim to having worked in all three branches of the government, and he is also the only person so far subpoenaed by Nadler who was not a member of the Trump campaign.
He supported Jeb Bush in the 2016 Republican primary. When Jared Kushner, the President's son-in-law and a White House senior adviser, asked Porter during the transition if he could be loyal to Trump given his track record, Porter replied he could be loyal to the office of the Presidency, according to a source with knowledge.
Footnotes in the Mueller Report indicate that Porter sat for two days of interviews with the special counsel's team. As staff secretary, his job was to vet any document the President signed. But it soon morphed into much more than that, it has been widely reported. Porter's glittering academic resume impressed the President who, according to three sources, increasingly relied on Porter for advice on a broad range of issues.
For example, when former Attorney General Jeff Sessions refused to un-recuse himself from the Mueller investigation, the Mueller report states that the President asked Porter about associate Attorney General Rachel Brand, whom Porter knew personally.
According to the report, the President asked Porter to find out if Brand was "on the team" and would be interested in becoming attorney general one day, or taking on the investigation herself.
Porter, the report said, did not do as the President asked and seek out Brand, because he understood that what he was being asked to do, thought it was not stated explicitly by the President, was to find someone to fire the special counsel or end the Russia investigation.
Porter was also sandwiched between an angry President and McGahn, according to the report, after McGahn refused to refute an article published by the New York Times that alleged the President had asked McGahn to fire the special counsel. McGahn had not only refused, but threatened to resign, according to the report. Trump had told Porter that the article was "bullsh**" and insisted to Porter that he tell McGahn to write a letter for the public file stating he had never asked McGahn to fire the special counsel. He told Porter that if McGahn did not do as directed "then maybe I will get rid of him."
According to the Mueller report, Porter told the President that he thought the matter would be best handled by the White House communications office. But after being pressed by the President, he went to McGahn and conveyed the message, which McGahn "shrugged off."
According to the Mueller report, Porter also talked with then-White House chief of staff John Kelly, who set up a meeting between the President and McGahn, during which McGahn told the President that the optics of firing him would be terrible. McGahn was not fired. He left the White House in October 2018.
Porter resigned from the White House in February 2018 amid allegations from two former wives of domestic abuse. Porter denied the allegations.
But for the next couple of months, the President continued to talk with Porter frequently and wanted him to return to the White House, according to a report in the New York Times. According to the book "Fear: Trump in the White House" by veteran Washington Post journalist Bob Woodward, Porter had acted as something of a guardrail against the President's more extreme positions, especially on a trade war with China and immigration.
Since then, it's not clear how often the President and Porter have talked or what the nature of their relationship is now. That could be one reason House Democrats want his testimony come September.