This is the thing that finally pushed Spicer over the edge? Not Trump serially humiliating him or scaling back his duties or openly interviewing possible replacements?

Not Pope-gate? The breaking point for Spicer was … a potential turf war with Anthony Scaramucci? What “turf” did Spicer have left?

Sean Spicer, the White House press secretary, resigned on Friday morning, telling President Trump he vehemently disagreed with the appointment of the New York financier Anthony Scaramucci as communications director…

Mr. Trump made the appointment over the objection of Mr. Priebus, who thought Mr. Scaramucci lacked the requisite organizational or political experience. But the president believed Mr. Scaramucci, a ferocious defender of Mr. Trump’s on cable television, was best equipped to play the same role in-house, and he offered him a role with far-reaching powers independent of Mr. Priebus’s.

Another piece of the puzzle?

Spicer also said to be furious that Trump gave big interview with NYT with only Hope Hicks present, and didn't tell Spicer.

— Gabriel Sherman (@gabrielsherman) July 21, 2017

Surely Spicer’s used to be snubbed that way by now. If, as some speculate, he seized on the Scaramucci news as a pretext for quitting, well, he’s had about 15 pretexts in the past and hasn’t used them. Why now?

Supposedly Spicer told Trump that appointing Scaramucci was a “major mistake”:

Spicer was telling folks last night he would resign if Scaramucci was hired. Said he didn't think Scaramucci could do the job. -source close

— Katy Tur (@KatyTurNBC) July 21, 2017

Scaramucci appears regularly on cable news but he’s a finance guy by trade, not a communications pro. Still, it’s hard to believe his inexperience would force Spicer to quit in a huff, particularly given how battered the White House press operations have been over the past few months by the president and the press. Spicer had already been all but supplanted by Sarah Huckabee Sanders as a public face of the administration. There’s no obvious reason why adding Scaramucci to the mix should cause him to freak out.

There’s some sort of history here, but it’s not clear yet what it is:

A natural schmoozer and fixture on the global financial scene from Davos to his own lavish hedge fund conference in Las Vegas, Scaramucci drew resistance from others in the White House, including chief of staff Reince Priebus, White House officials said…

“Just hiring Anthony is telling Reince beat it, go find another job,” said the source, who cited the tense relationship between the two…

Scaramucci was once one of the RNC’s top donors when Priebus was chairman, but Priebus’ role in trying to block him from joining the administration has been a sore point between the two.

Spicer was chief spokesman at the RNC when Reince was RNC chairman. Priebus persuaded Trump to bring him over to the White House as press secretary after he was appointed chief of staff, so naturally Spicer is loyal to Priebus. Even so, Reince hasn’t quit (yet) over Scaramucci; Spicer seems to find him more objectionable than Priebus does. Why? Why would two RNC guys have such hard feelings towards someone who used to bankroll them?

Steve Bannon reportedly also objected to Scaramucci’s appointment, although that’s less of a mystery than the Priebus/Spicer revolt. Bannon is already uneasy with financiers like Gary Cohn being brought into the White House and pushing Trump away from nationalism and towards “globalism.” Scaramucci, in fact, backed several Trump opponents in the primaries before finally swinging around behind the nominee last summer. Bannon might legitimately fear Scaramucci’s ideological influence. But not Priebus or Spicer.

Here’s one reasonable theory on why Spicer might have balked and why Reince might soon follow him:

My best guess is they think a Trump pal w/ no political experience feeds POTUS' worst instincts.

— Christian Vanderbrouk (@UrbanAchievr) July 21, 2017

Right. What Trump needs more than ever right now, with the Russiagate probe intensifying, is someone who’ll keep him on message. A guy who’s being appointed because he’s a pal and knows how to schmooze isn’t that someone. Another theory:

Spicer would essentially be doing two jobs and reporting to Scaramucci.

— La Jolla Liberal™️ (@LaJollaLiberal) July 21, 2017

If Scaramucci is there basically just to shoot the breeze with Trump and attack his opponents via sporadic cable news hits, Spicer might be stuck with the worst of all worlds — effectively doing the hard work of the communications job and (part of) the press secretary job while Scaramucci enjoys the limelight. No thanks.

He lasted exactly six months and one day. Today, in fact, is the half-year anniversary of his famous first presser, in which he berated the media for underestimating the size of Trump’s inaugural crowd. By the way, if you believe Axios, Trump didn’t even tell Priebus of his plans to appoint Scaramucci until they were already well in motion. If you’ll excuse me, I’m off to pre-order Spicer’s as-yet-unwritten tell-all on Amazon.

Update: A good reason to give a guy a hugely influential spokesman role for the U.S. government:

Source close to WH press shop tells me Trump "wanted to give Scaramucci something to do because he likes him on TV"

— Kate Nocera (@KateNocera) July 21, 2017

Update: Man. What happened here?

Scaramucci has previously had a tense and fraught relationship with both Spicer and White House chief of staff Reince Priebus, who both vehemently objected to Trump’s decision to install Scaramucci in the top communications job. Scaramucci has coined a particularly crude nickname for Preibus, and Preibus previously blocked the financier from several other top White House roles.

Update: Here’s Scaramucci showing off his PR chops in 2015, ripping all over Trump on Fox Business:

Update: Not a lot of regard for “Mooch” among the existing inner circle — although Jared and Ivanka seem to like him.

According to three senior officials with knowledge of the situation, they and other top aides worried that the Scaramucci hiring would perpetuate the notion of “amateur hour” in the West Wing. White House officials who opposed Scaramucci’s planned rise in Trump’s ranks have referred to the incoming new addition as a “joke” and as a Trump-world “hanger-on” who isn’t qualified for the job and is unprepared to handle the near-constant communications crisis dogging President Trump, senior White House aides noted…

“As much as the big man hates to hear it, a Beltway mentality would serve him well right now,” a senior White House official told The Daily Beast. Scaramucci “obviously isn’t that.”

Update: An oldie but goodie from Scaramucci’s Twitter account.

https://twitter.com/Scaramucci/status/232349114979975168

Update: This doesn’t bode well for Bannon’s influence in the White House:

Bannon told Scaramucci "over my dead body" will he get the job – two sources 1 in WH and 1 out tell @Sruhle and me.

— Katy Tur (@KatyTurNBC) July 21, 2017

Coincidentally, or maybe not coincidentally, Politico had a piece out this morning about Bannon in “self-exile” from Trump’s inner circle lately, declining to join him on his trip to the G20 and dodging top-level meetings on trade. Supposedly Trump is “livid” at the attention Bannon’s getting lately from the media due to the new book that’s out about him. Politico’s theory is that Bannon is lying low knowing that Trump is in house-cleaning mode right now, not wanting to be part of any imminent White House purge. But maybe the Scaramucci decision signals that that’s unavoidable.

Update: What the hell?

#SPICER scheduled to appear exclusively on @seanhannity tonight.

— Matt Finn (@MattFinnFNC) July 21, 2017

Why would a guy who just quit the White House in disgust be booked for the White House’s most loyal primetime news show?

Update: Why not resign effective immediately? Huckabee Sanders is there to do the briefings. This is just 40 more days of awkwardness.

It's been an honor & a privilege to serve @POTUS @realDonaldTrump & this amazing country. I will continue my service through August

— Kayleigh McEnany 45 Archived (@PressSec45) July 21, 2017

Update: Ah, here’s the reason for the Hannity spot. They’re going to present a united front.

On Hannity tonight at 10 pm et on Fox: Sean Spicer, Reince Priebus and Anthony Scaramucci.

— Chad Pergram (@ChadPergram) July 21, 2017

Update: No surprise. Sarah Huckabee Sanders is the new White House press secretary.