One of Mr Porter's former wives, Jennifer Willoughby, obtained a restraining order against him, while the other, Colbie Holderness, presented a photograph of herself with a black eye, which she said came from being hit by Mr Porter while the couple was on vacation in Italy.
That represents a sharp break with past practice, in which White House counsels undertook elaborate vetting of senior advisers before they were hired - and looked into any serious allegations that surfaced thereafter.
Routinely, Trump has accepted claims of innocence from men facing similar allegations, including Fox News head Roger Ailes, anchor Bill O'Reilly and former Alabama Senate candidate Roy Moore, who was accused of inappropriate contact with teenage girls.
"That dynamic leaves many simply unwilling to consider the possibility that he has engaged in acts of violence, and when people aren't willing to imagine that, the easiest thing to do is disbelieve the woman making these allegations", Martin said. President Trump - or "Teflon Don" as some refer to him - has an almost-reflexive tendency to disregard when the media suggests things in the White House have gone to far.
Porter's abrupt departure raised questions about how long it took Trump's team to act on the accusations.
Vice President Mike Pence, who is attending the Olympics in South Korea, tried to distance himself from the issue, but also stressed in an NBC interview that "there is no tolerance in this White House , no place in America for domestic abuse".
"Rob Porter has been effective in his role as staff secretary". CNN's Jake Tapper tweeted back: "In point of fact, 2 ex-wives talking on the record to journalists and to the Federal Bureau of Investigation and one ex-girlfriend on background, with a photo of a black eye and a police report, is not 'a mere allegation'".
The White House did not immediately respond to CNN's request for comment on the letter.
"But the irony for Kelly may be that the credibility that makes him a singular asset in this White House may have been irreparably damaged by his work in it".
But on Wednesday afternoon, Sarah Huckabee Sanders, the White House press secretary, and other aides had maintained to reporters that the White House fully backed Porter, who they said was leaving of his own accord.
As the meeting broke up, Hicks loudly complained about what had transpired, using an expletive, a person briefed on the meeting said.
Kelly is not ready to explicitly offer a resignation, according to a person familiar with his thinking.
"The perception of Kelly as above politics has been critical to his success in the West Wing. And we hope he has a wonderful career and he will have a great career ahead of him". He also expressed his frustration with both Kelly and Hicks.
"Kelly's luster has slowly eroded during his roughly six months as Trump's top staffer - and some White House aides worry it may be acutely painful, considering he takes personal pride in his honor as a lifelong public servant".
Mulvaney, who also serves as the acting director of the Consumer Financial Protection Bureau, said he doesn't want Kelly's job.