Brad Parscale, Donald Trump's campaign manager for the US election in 2020, posted the letter to Twitter on Thursday, where it received hundreds of retweets within minutes. The letter requested information about Facebook's and Twitter's efforts to "prevent political bias" on their social networks.
The letter was signed by Parscale and Ronna McDaniel, the chairwoman of the Republican National Committee.
"We recognize that Facebook and Twitter operate in liberal corporate cultures," the letter reads. "However, rampant political bias is inappropriate for a widely used public forum."
The letter calls for an answer from the two companies by June 18.
Twitter declined to comment. Facebook didn't respond to a request for comment.
You can see the full letter here:
Conservatives have said that Facebook and Twitter are actively stifling their voices on social media, with politicians bringing it up to Zuckerberg on three separate occasions in public hearings. At a congressional hearing about Cambridge Analytica, Sen. Ted Cruz, a Republican from Texas who used the data analytics firm,, two Trump-supporting personalities on Facebook. So did at least five other US lawmakers.
At the, the UK's representative, Nigel Farage, did the same, accusing Facebook's algorithm of censoring conservatives.
The letter on Thursday also pointed to Twitter deleting followers from popular conservative accounts. While people were outraged they'd lost thousands of followers, Twitter said the mass deletion was not political,.
On Friday, Parscale sent an email to members of a mailing list associated with the Republican National Committee and the Trump Make America Great Again Committee. In it, he said he'd print a letter later in the evening demanding that "Silicon Valley social media elites" stop censoring users and engaging in "liberal bias."
"Social media platforms are now flagging conservatives who speak up on behalf of the President's America First agenda as 'offensive content,'" Parscale said, and he asked people to add their signatures to the letter.
"I'm sending a letter signed by all the patriots in America who refused to be silenced," Parscale said in an accompanying action alert posted online.
A Facebook representative said the social network is a "platform for all ideas," and doesn't suppress content based on political views "because doing so would be directly contrary to Facebook's mission and our business objectives."
Google, the Democratic National Committee and the Republican National Committee didn't immediately respond to requests for comment about Parscale's call to action. Twitter had no public comment.
Though yesterday's letter about Facebook and Twitter complains that the platforms have censored conservative viewpoints, some Trump supporters have pointed to the social networks as being key to his success.
Late last year, Parscale told CBS' 60 Minutes that Facebook helped Trump win the White House, and in his opening remarks to Zuckerberg, Farage told the Facebook CEO, "it's true that through Facebook and other forms of social media, there is no way that Brexit or Trump or the Italian elections could ever possibly have happened."
Others have said Trump has. On Wednesday, however, a federal judge ruled the who are critical of his policies from following him on the social network.
The Thursday letter also calls for details on Facebook's voter registration push. The RNC and Parscale want to know who Facebook is pushing the ads toward, with concerns that only Democratic voters would be urged to register.
First published May 24, 8:08 a.m. PT.
Updates, 9:21 a.m.: To add Twitter's response; May 25 at 6:27 p.m.: Includes information on Parscale's Friday call to action; May 25 at 6:54 p.m.: Adds comment from Facebook.
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