The day before the midterm elections, Facebook took down a virulently anti-immigrant ad paid for by President Donald Trump, which mischaracterizes refugees walking through Mexico toward the US as violent criminals. “America’s future depends on you,” the voiceover says, ending with a plea to “vote Republican.” NBC also took the ad off air on Monday after criticism from stars of NBC shows. And even Fox News stopped airing it on Monday, too. CNN rejected it from the start, on the grounds that it was racist.

Facebook says the ad violated its policy against “sensational content,” which prohibits ads that contain “shocking, sensational, disrespectful or excessively violent content.” Facebook did not specify what aspects of Trump’s ad it found to be sensational.

Immigration has become a major talking point for Republican campaigns across the country this election season as politicians try to rally their base in what is expected to be a number of close races. Trump is not the only campaign to run political ads on Facebook that stoke fears about immigrants making their way to the US border. Arizona Republican congressional candidate Wendy Rogers, for example, is currently running ads that feature many of the same images of so-called “illegal aliens,” as well as footage of violent mobs burning cars and breaking barricades. When asked why Trump’s ad was deemed sensational but Rogers’ was not, a Facebook representative didn’t immediately have an answer, but asked WIRED to send over the specific videos so they could take a closer look. (Update: On Tuesday morning, Facebook told WIRED that it had pulled one of Rogers' ads. "This ad violates Facebook's advertising policy against sensational content so we are rejecting it," a spokesperson said. "While the video is allowed to be posted on Facebook, it cannot receive paid distribution." Facebook did not comment on how the ad got approved in the first place.)

And Trump’s ad, while no longer allowed to have paid promotion, is still very much on Facebook. The 30-second spot was posted by Trump campaign manager Brad Parscale and shared by Trump’s official page on Monday; in five hours, it had more than 446,000 views. More than a million people have viewed the longer version of it from President Trump’s official Facebook page since November 1. Six million people have viewed the same version he shared in a tweet the president sent out on Halloween. More than 800,00 have viewed the ad from a tweet shared by Donald Trump Jr. on November 3.

(It appears the ad never ran as a promoted tweet on Twitter, and a Twitter spokesperson told WIRED that it would violate Twitter’s “inappropriate content policy” for ads if the Trump campaign tried to pay to promote it. That policy disallows anything that’s disturbing, shocking, threatening, or distasteful, among other things.)

Social media companies have different standards for content shared in organic posts than they do for ads. The rules for ads are stricter.

After the 2016 presidential election, when it belatedly realized that at least 3,000 ads had been purchased by Russians intent on influencing US democracy, Facebook vowed to do better. It voluntarily raised the standards for political ads on its site, and created a searchable database to make ad buys more transparent, including adding a “Paid for by” feature that shows who paid for a given ad. All of this is good, and important---as it’s been clear since way back in 2010 when Facebook did a randomized vote-mobilization test on 61 million unwitting Facebook users that these ads can have real impact.