ASSOCIATED PRESS Trump said last week that he regrets hurting people's feelings. But that doesn't mean he's going to stop insulting people. (AP Photo/Gerald Herbert)

WASHINGTON ― Just days after the media heralded a “new Trump” because he said he felt bad for hurting people’s feelings, Donald Trump is back at it again with some mean tweets.

Trump tuned into MSNBC’s “Morning Joe” on Monday and didn’t like what he saw, so he threatened to “tell the real story” about co-hosts Joe Scarborough “and his very insecure long-time girlfriend,” Mika Brzezinski.

Some day, when things calm down, I'll tell the real story of @JoeNBC and his very insecure long-time girlfriend, @morningmika. Two clowns! — Donald J. Trump (@realDonaldTrump) August 22, 2016

In another tweet, he called Brzezinski an “off the wall, a neurotic and not very bright mess!”

Tried watching low-rated @Morning_Joe this morning, unwatchable! @morningmika is off the wall, a neurotic and not very bright mess! — Donald J. Trump (@realDonaldTrump) August 22, 2016

Scarborough responded by tweeting that Trump should look in the mirror.

On Thursday, Trump forayed into seeming presidential by expressing contrition apparently for the first time.

“Sometimes, in the heat of debate and speaking on a multitude of issues, you don’t choose the right words or you say the wrong thing,” he said during a speech in Charlotte, North Carolina. “I have done that. And believe it or not, I regret it. And I do regret it, particularly where it may have caused personal pain. Too much is at stake for us to be consumed with these issues.”

Although Trump never specified which of his many, many insults he regretted, his shift in tone won him many favorable headlines regarding his latest apparent “pivot.” Monday’s mean tweets show his tendency to return to form.

Trump once confessed during a phone interview on “Morning Joe” that he has very thin skin.

Arthur Delaney is a co-host of “So That Happened,” the HuffPost Politics podcast:

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.