Twitter is banning all political advertising from its service, saying social media companies give advertisers an unfair advantage in proliferating highly targeted, misleading messages.
In a series of tweets announcing the new worldwide policy, Twitter chief executive Jack Dorsey said: "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."
Facebook has faced criticism since it disclosed earlier in October that it will not fact-check ads by politicians or their campaigns.
READ MORE: Facebook staff urge company to reverse policy allowing politicians to make false claims in adverts
Chief executive Mark Zuckerberg told US Congress last week that politicians have the right to free speech on Facebook.
In Facebook's earnings conference call, which began less than an hour after Mr Dorsey's tweet, Mr Zuckerberg issued an impassioned monologue about what he called Facebook's deep belief "that political speech is important" and stood by the company's decision to run unchecked political ads.
"Some people accuse us of allowing speech because they think all we care about is making money, and that's wrong," Mr Zuckerberg said on the earnings call.
"I can assure you that from a business perspective, the controversy this creates far outweighs the very small percentage of our business that these political ads make up."
To put that in perspective, he added, Facebook's recent five billion dollars Federal Trade Commission fine was more than ten times that.
"This is complex stuff. Anyone who says the answer is simple hasn't thought about the nuances and downstream challenges," he said.
"I don't think anyone can say that we are not doing what we believe or we haven't thought hard about these issues."
READ MORE: Facebook removes over 100 adverts for Donald Trump’s businesses
The issue suddenly arose in September when Twitter, along with Facebook and Google, refused to remove a misleading video ad from US president Donald Trump's campaign that targeted former vice president Joe Biden, a leading Democratic presidential candidate.
In response, Democratic Senator Elizabeth Warren, another presidential hopeful, ran an ad on Facebook taking aim at Mr Zuckerberg.
The ad falsely claimed Mr Zuckerberg endorsed Mr Trump for re-election, acknowledging the deliberate falsehood as necessary to make a point.
Critics have called on Facebook to ban all political ads. This includes CNN chief Jeff Zucker, who recently called the policy of allowing lies ludicrous and advised the social media giant to sit out the 2020 election until it can figure out something better.
Google did not have immediate comments on Twitter's policy change.
Twitter currently only allows certified campaigns and organisations to run political ads for candidates and issues. The latter tend to advocate on broader issues such as climate change, abortion rights and immigration.
The company said it will make some exceptions, such as allowing ads that encourage voter turnout. It will describe those in a detailed policy it plans to release on November 15.
Twitter's policy will start on 22 November.
Mr Trump's campaign manager called Twitter's change a "very dumb decision" in a statement on Wednesday.
"This is yet another attempt to silence conservatives, since Twitter knows President Trump has the most sophisticated online program ever," campaign manager Brad Parscale said.
The presidential campaign for Mr Biden said it was "unfortunate" that companies would think the only option was to completely ban political ads.
"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," Bill Russo, the deputy communications director for Mr Biden's campaign said in a statement.