However, in a statement Wednesday night, Kelly said he was "shocked" by the allegations against Porter, although he did not denounce his aide outright. He is a friend, a confidante and a trusted professional.
"I actually had difficulty answering that question because I believed that the people who had the power to blackmail him would be women who had been in personal relationships with him, so in short the answer could be maybe", she said. "The President and Chief of Staff have full confidence in his abilities and his performance", she said.
Shah would not "get into specifics" of who knew what and when, but said Kelly "had not seen images" released by Colbie Holderness, Porter's first wife, until they were published Wednesday. The statement was reportedly drafted in part by White House Communications Director Hope Hicks, who's in a romantic relationship with Porter.
Congressional Democrats have been trying for months to get information about the administration's security-clearance process, including the number of aides granted interim clearances because of issues uncovered in background checks by the Federal Bureau of Investigation. Talking about his resignation, he has said that he "will seek to ensure a smooth transition when he leaves the White House".
Sources told CBS News that the Federal Bureau of Investigation informed the White House about the abuse allegations in November - so how could the news have taken so long to filter through the chain of command? Porter denied the allegations but resigned on Wednesday.
Now the White House is under scrutiny over when and where officials knew about Porter's history.
Shah, trying to clean up the mess Thursday during his first turn at the briefing podium, would not confirm if Kelly knew about the allegations before this week and, if so, for how long.
Rob Porter, 40, is a White House staff secretary who worked closely with Trump, often accompanying him on official travel. "In this instance, in the case of Rob Porter, we relied on the background check investigative process".
"I have been transparent and truthful about these vile claims, but I will not further engage publicly with a coordinated smear campaign", he added.
White House Counsel Don McGahn was also aware of the allegations but did not act.