Top Republicans are privately worried about a new threat to President Trump’s campaign: the possibility of Facebook pulling a Twitter and banning political ads. 

• Why it matters: Facebook says it won't, but Axios' Sara Fischer points out that future regulatory pressure could change that. If Facebook were to ban — or even limit — ads, it could upend Trump’s fundraising and re-election plan, GOP officials tell me.
• Trump relies heavily — much more so than Democrats — on targeted Facebook ads to shape views and raise money.

Red flag: Kara Swisher, of Recode, the super plugged-in tech writer, predicted on CNBC's "Squawk Box" that Mark Zuckerberg will ultimately buckle on allowing demonstrably false political adds on Facebook: "He's going to change his mind — 100% ... [H]e's done it before."

• Twitter this week announced a ban on political and advocacy ads. ("Platforms give pols a free pass to lie," by Scott Rosenberg)
• Trump campaign manager Brad Parscale ridiculed the decision ("yet another attempt by the left to silence Trump and conservatives"), signaling the wicked backlash that would hit Zuckerberg.

Why it would hurt Trump: His campaign has mastered the art of using Facebook’s precision-targeting of people to raise money, stir opposition to impeachment, move voters and even sell Trump shirts and hats.

• The Trump campaign often uses highly emotional appeals to get clicks and engagement, which provides valuable data on would-be voters and small-dollar donors.

Trump campaign communications director Tim Murtaugh told me: "We’ve always known that President Trump was too successful online and that Democrats would one day seek to wipe him off the Internet."

• "That’s why we’ve invested so heavily in building up our data to allow us to communicate with millions of voters away from any third-party platforms like Facebook."
• "Democrats demanding internet platforms shut down political advertising will guarantee Trump’s victory in 2020. They’re idiots."

By the numbers: The Trump campaign has spent $15.7 million dollars on Facebook ads this year, according to data from progressive advertising firm Bully Pulpit Interactive.

• The next closest Democratic spender is billionaire Tom Steyer, who has so far spent less than half of that.

Go deeper: "Where Trump's Facebook spending goes," by Sara Fischer.

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The Democratic 2020 candidates drew more social media attention than ever in October — but were still swamped by President Trump’s ever-present dominance of what we share and debate, according to data from NewsWhip exclusively provided to Axios' Neal Rothschild.

• Why it matters: Trump attracted three times the attention of all the Democratic candidates combined, underscoring how he consumes the social media conversation. 

By the numbers: The 2020 Democratic candidates picked up a combined 58 million social media interactions (likes, comments, shares) on stories about them. But that's dwarfed by Trump's 181 million, the NewsWhip data shows. 

• As has been the case since he entered the Republican field in 2015, much of the online attention on Trump has been negative.
• But the net effect of higher interactions means many more Americans learning about Trump's comments, actions and policies and making determinations about them, rather than doing so for his Democratic challengers.
• This reality extends beyond these measures: The same dynamic plays out on cable news, and Trump's Twitter account is a bigger amplifier than any of his competitors'.

Between the lines: That Trump has this much share of attention is not just a consequence of holding the presidency.

• In the month before the 2016 election, Trump had more than seven times the interactions of President Obama, according to NewsWhip data.

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The Trump administration plans to finalize a ban on almost all flavored vaping products next week, with exemptions only for tobacco and menthol flavors, sources familiar with the plan tell Jonathan Swan and Sam Baker.

• Why it matters: Conservatives, including Trump campaign manager Brad Parscale, had urged President Trump to back away from such a sweeping crackdown. But sources said the president was briefed by senior health officials on the plan at a White House meeting Thursday.

Senior officials expect the FDA to issue its long-awaited guidance next week.

• As with any decision, it's possible Trump could change his mind at the last minute.

The new rules will likely prohibit the sale of all flavored vaping products except tobacco and menthol flavors.

• Senior health officials believe that those flavors are more popular with adults than with children, and curbing the explosion in youth vaping is the point of this regulatory crackdown.
• Mint-flavored products would have to come off the market, according to sources familiar with the planning.

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These won't be needed: Beto O'Rourke campaign signs were piled up in Des Moines ahead of the big Iowa Democratic Party dinner.

• O'Rourke dropped out yesterday: "Though it is difficult to accept, it is clear to me now that this campaign does not have the means to move forward successfully."

Go deeper.

A growing number of Senate Republicans are ready to acknowledge a quid pro quo on Ukraine, the WashPost's Rachael Bade and Seung Min Kim report.

• "In this shift in strategy to defend Trump, these Republicans are insisting that the president’s action was not illegal and does not rise to the level of an impeachable offense."

Why it matters: This is an important story because it shows that even if Democrats show with certainty there was a quid pro quo, Republicans will still stand with Trump.

"MIT president Rafael Reif, in the latest fallout over the school’s connections to disgraced financier Jeffrey Epstein, says women at the prestigious university feel belittled, minority and LGBTQ members feel excluded, and staff are bullied by star faculty," the Boston Globe's Deirdre Fernandes reports.

• Why it matters: "Reif said in a letter to the community ... that the controversy has unearthed deeply rooted cultural challenges with 'searing clarity.'

From the letter: "When ­— on top of the hard work they came here to do — many in our community contend with disrespect, exclusion, stereotyping, harassment and a structural lack of representation, it is clear we still have a long way to go to achieve our ideal of "One MIT.'"

• Read the letter. ... Read the story.

Nats reliever Sean Doolittle, long known for liberal opinions and his willingness to share them, is the first player to say that he won't join the team at the White House ceremony on Monday, the WashPost reports:

• "There’s a lot of things, policies that I disagree with, but at the end of the day, it has more to do with the divisive rhetoric and the enabling of conspiracy theories and widening the divide in this country. ... I just can’t do it."