"I think it's fair to say we all could have done better dealing with this over the last few days," Shah said.
Porter resigned Wednesday and quickly left the White House Thursday after domestic abuse allegations by his two ex-wives surfaced in a British tabloid. Porter has denied the claims.
White House officials first defended Porter in the immediate aftermath of the allegations on Monday and Tuesday.
"Rob Porter is a man of true integrity and honor and I can't say enough good things about him," White House Chief of Staff John Kelly said in a statement Tuesday. "He is a friend, a confidante and a trusted professional. I am proud to serve alongside him."
Then a photo of one of Porter's ex-wives with a black eye was released Wednesday in addition to the British tabloid story published on Monday and Tuesday in The Daily Mail, and Kelly seemed to walk back his comments about Porter.
By Wednesday night, Kelly released a second statement, amid reports that administration officials kept Porter on the job despite being aware of the alleged abuse. Porter's first wife, Colbie Holderness, and his second, Jennifer Willoughby, told CNN they were contacted by the FBI last year while Porter was applying for a security clearance to work at the White House. At least one of the women told the FBI about the alleged domestic violence, according to CNN.
“I was shocked by the new allegations released today against Rob Porter. There is no place for domestic violence in our society,” Kelly said Wednesday night. “I stand by my previous comments of the Rob Porter that I have come to know since becoming chief of staff, and believe every individual deserves the right to defend their reputation.”
President Donald Trump speaks with White House Staff Secretary Rob Porter (C) and Sen. Mike Lee (R-UT) (R) as they return to the White House December 4, 2017 in Washington, DC. President Trump traveled to Utah to announce his plan to shrink the Bears Ears and Grand Staircase-Escalante national monuments.
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. But critics insist Kelly must have known something because Porter never received full security clearance -- only a temporary clearance, an unusual situation for an aide inside the president’s inner circle.
"He became fully aware of these allegations yesterday," Shah said of Kelly, later adding that he had "not seen images prior to the statement on Tuesday night," referring to the picture of one of Porter’s ex-wives with a black eye.
Shah defended the administration, claiming it wasn’t the photographic evidence of the alleged abuse that changed Trump officials’ tone toward Porter.
“We do take allegations of misconduct, of domestic violence, other issues like that very seriously,” he said. “In this instance, in the case of Rob Porter, we relied on the background check investigative process. That process hadn't been completed. We're relying on the information that we had.”
Holderness told The Daily Mail that Porter was verbally abusive throughout their relationship, which started in 2000, but that things escalated after they wed in June 2003. She said Porter kicked her during their honeymoon and, during a 2005 vacation in Italy, punched her in the face.
Willoughby, who married Porter in November 2009 and separated from him in early 2010, told The Daily Mail that Porter was verbally abusive.
Willoughby obtained a protective order against Porter in June 2010 after she said he violated their separation agreement and refused to leave her apartment, according to court records obtained by The Daily Mail. In the complaint, Willoughby said Porter punched in a glass door while she was locked inside the apartment, but left after he heard she was on the phone with police.
She told the Mail that in December 2010, he dragged her out of a shower while she was naked in order to yell at her.
The couple was divorced in 2013.
Porter, 40, is a former chief of ctaff for Utah Sen. Orrin Hatch, a Harvard graduate and a former Rhodes Scholar.