On the day Hope Hicks announced she would be leaving her post as White House communications director, she was "a puddle of tears" during the White House communications meeting Wednesday, according to one eyewitness. President Trump was angered by Hicks' testimony before the House Intelligence Committee -- angered by the fact that she admitted to the panel over the course of nine hours of testimony that she told "white lies" on his behalf. It is doubtful that this would have caused her to resign.

Mr. Trump yelled at her frequently during his first year in office. But his outbursts did not faze her, and in fact, she often withstood his rages in order to protect others in the White House communications shop. She always knew that she could endure it, and that he could never stay mad at her for long. Senior staffers would consult with Hicks on how to anticipate the president's reaction on tough subjects they had to raise with him.

According to two knowledgeable sources, there is a leading candidate to replace Hicks -- Mercedes Schlapp, who is currently the head of strategic communications for the White House.

Several sources tell CBS News that in addition to her House Intel testimony, it's believed that Hicks succumbed to renewed pressure related to the Rob Porter situation. She had been dating the White House staff secretary during the period when it was revealed that allegations that he had abused his two ex-wives were standing in this way of his permanent security clearance.

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There's also the perception that White House chief of staff John Kelly is moving against those closely aligned with Jared Kushner and Ivanka Trump. Kushner was forced to give up access to the most classified information over the delay in his own permanent security clearance.

As Major Garrett reported Wednesday on "CBS This Morning," Kelly's security clearance spat with Kushner is part of this power play. Hicks' departure and the Kushner-Kelly security skirmish are seen by Garrett's sources as "two wins in one week" for Kelly. Reed Cordish's departure from the Office of American Innovation -- which was run by Kushner -- would also fall into this category. So would the departure of Josh Raffel. All were loyalists of Kushner and Ivanka Trump.

There are those in the White House who also see White House counsel Don McGahn as a force here. Though he and Kelly clashed over Porter and the security clearance issue, they have found common cause against Kushner and Ivanka Trump. White House veterans, the few who remain, say McGahn began lobbying Kelly against Kushner and Ivanka early on, having lost former chief of staff Reince Priebus and former White House chief strategist Steve Bannon as allies. Late last year, Kelly made it clear he thought Kushner and the president's daughter had outsized roles in the White House and was not afraid to make that impression known.

CBS News' Major Garrett contributed to this report.