"We believe political message reach should be earned, not bought," Twitter Chief Executive Officer Jack Dorsey wrote on the platform.
Twitter is set to ban all political advertising on the platform from November 22, Chief Executive Officer Jack Dorsey announced on Wednesday.
In a series of 11 tweets, Dorsey laid out the reasons why the company was changing its policy, emphasising that it was not a question of freedom of expression but rather, in his view, about "paying for reach".
"We believe political message reach should be earned, not bought," Dorsey said.
Dorsey said it wasn't "credible" to say that they were working to prevent "misleading" information on the platform at the same time that they allow people to pay for targeted political advertising.
"We’re well aware we‘re a small part of a much larger political advertising ecosystem. Some might argue our actions today could favor incumbents. But we have witnessed many social movements reach massive scale without any political advertising. I trust this will only grow," Dorsey wrote.
The platform also plans to include "issue advocacy", which it defines as adverts that "refer to an election or a clearly identified candidate" or those that "advocate for legislative issues of national importance."
But many people asked on social media about "issue advocacy" and how Twitter would define them.
"Climate change? Gay marriage? Equal pay?" Instagram Head Adam Mosseri asked in another Twitter thread.
Indeed, Twitter includes issues such as abortion, civil rights, climate change, guns, healthcare, immigration, national security, social security, taxes, and trade under its political content policies.
"The challenge with banning “issue ads” is that you catch every well-meaning NGO as well," wrote Alex Stamos, Facebook's former Chief Security Officer.
There will be some exceptions to Twitter's policy, Dorsey said. Ads in support of voter registration, for instance, will still be allowed.
Twitter plans to introduce the full policy by November 15 and will start enforcing the policy on November 22.
Many observers on social media hailed Twitter's announcement as one that would put the pressure on other companies to do the same.
The decision comes as technology companies are increasingly under fire about allowing misinformation on their platforms. Facebook has been criticised, for instance, for exempting politicians from third-party fact-checking.
In a notable exchange during a U.S. congressional hearing, Facebook CEO Mark Zuckerberg was grilled on the policy by Representative Alexandria Ocasio-Cortez.
Zuckerberg stumbled through her questions on political fact-checking, stating that although "lying is bad", he believed that "people should be able to see for themselves what politicians that they may or may not vote for are saying to judge their character for themselves".
Twitter's Chief Financial Officer Ned Segal said that the policy would not affect the company's revenue, stating that the company made the choice "on principle".