will stop all political advertising on its platform, getting out of a business that has been fraught with controversy over questions of whether spots need to be fact checked and verified.

“A political message earns reach when people decide to follow an account or retweet,” Twitter CEO Jack Dorsey wrote on Twitter on Wednesday. “Paying for reach removes that decision, forcing highly optimized and targeted political messages on people. We believe this decision should not be compromised by money.”

He added, “While internet advertising is incredibly powerful and very effective for commercial advertisers, that power brings significant risks to politics, where it can be used to influence votes to affect the lives of millions.”

Twitter’s new policy diverges from that of Facebook, which accepts political advertisements and does not fact check them. That has been a simmering issue headed into the 2020 presidential campaign, and CEO Mark Zuckerberg has been criticized by candidates like Joe Biden and Elizabeth Warren for the policy, which they say contributes to an atmosphere of misinformation.

Zuckerberg defended the policy last week in an appearance before a House Committee.

“Our policy is we do not fact check politicians’ speech, and the reason for that is that we believe that in a democracy it is important that people can see for themselves what politicians are saying,” he said.

He continued to defend the company’s policy on Facebook’s earnings call, while noting that such spots account for just a small sliver of the company’s revenue.

As federal investigators uncovered the extent of Russian sources to influence the 2016 election, including the purchase of ads under the guise of faux political groups, Twitter announced a set of new guidelines that included a certification process. Twitter also publishes the amount that candidates have spent on promoted tweets. For instance, Pete Buttigieg’s campaign has spent $382,000, Joe Biden’s campaign shelled out $617,000 and Bernie Sanders’ campaign has been charged $314,000.

But Dorsey wrote that internet political ads “present entirely new challenges to civic discourse: machine learning-based optimization of messaging and micro-targeting, unchecked misleading information, and deep fakes. All at increasing velocity, sophistication, and overwhelming scale.”

“These challenges will affect ALL internet communication, not just political ads. Best to focus our efforts on the root problems, without the additional burden and complexity taking money brings. Trying to fix both means fixing neither well, and harms our credibility.”

Dorsey also took aim at Zuckerberg’s defense of Facebook taking political spots.

“It’s not credible for us to say: ‘We’re working hard to stop people from gaming our systems to spread misleading info, buuut if someone pays us to target and force people to see their political ad…well…they can say whatever they want!'”

For instance, it‘s not credible for us to say: “We’re working hard to stop people from gaming our systems to spread misleading info, buuut if someone pays us to target and force people to see their political ad…well…they can say whatever they want! 😉” — jack 🌍🌏🌎 (@jack) October 30, 2019

Facebook has deployed fact-checkers to gauge the veracity of content on its platform, but that does not apply to candidate ads.

Dorsey also called for “more forward looking ad regulation,” beyond that of mere transparency of what spots are running on platforms. He wrote that regulators “need to think past the present day to ensure a level playing field.”

“This isn’t about free expression,” Dorsey wrote. “This is about paying for reach. And paying to increase the reach of political speech has significant ramifications that today’s democratic infrastructure may not be prepared to handle. It’s worth stepping back in order to address.”

The ban on political advertising will cover not just candidate spots but issue ads. The latter have proven to be especially problematic for platforms, as in a number of cases it has been difficult to discern their true sources of funding.

Dorsey said that the new policy would go into effect on Nov. 22.

Biden’s campaign complained about Facebook’s policy after it accepted a spot from the reelection campaign of President Donald Trump. Biden’s campaign argued that the ad contained falsehoods about Biden and his son, Hunter, who was on the board of a Ukrainian gas company.

CNN rejected the spot, but other outlets did not. Broadcast stations, meanwhile, have to accept political candidates’ spots under a set of FCC guidelines that regulate ad rates and other access.

Trump’s campaign blasted Twitter’s new policy, calling it a “dumb decision for their stockholders.”

“Will Twitter also be stopping ads from biased liberal media outlets who will not run unchecked as they buy obvious political content meant to attack Republicans?” campaign manager Brad Parscale said in a statement. “This is yet another attempt to silence conservatives, since Twitter knows President Trump has the most sophisticated online program ever known.”

But the Trump campaign actually has spent little on Twitter spots this cycle — just $6,300, and another $266 billed to Parscale’s firm, Parscale Strategies, according to the company’s disclosure.

Bill Russo, spokesman for Biden’s campaign, also responded. In a statement, he said, “We appreciate that Twitter recognizes that they should not permit disproven smears, like those from the Trump campaign, to appear in advertisements on their platform.”

He added, “It would be unfortunate to suggest that the only option available to social media companies to do so is the full withdrawal of political advertising, but when faced with a choice between ad dollars and the integrity of our democracy, it is encouraging that, for once, revenue did not win out.”

Steve Passwaiter, vice president of the Kantar Media’s Campaign Media Analysis Group, said that the impact on the presidential campaign would be minimal.

“Twitter is still going to allow candidates to have their accounts; just no advertising,” he said via email. “Twitter isn’t that big of a player in the ecosystem.”

He believes that it will cause more thought on the digital side “as to whether it’s worth taking political ads.”

“Seeing what’s happened to Facebook, why wouldn’t you give it some serious thought?”