On Twitter, Mr. Trump’s adherents targeted one of the company’s executives for old tweets in which he had criticized the president and other Republicans. On Capitol Hill, lawmakers including Senator Marco Rubio, Republican of Florida, and Senator Josh Hawley, Republican of Missouri, said they would move to regulate Twitter.
In right-wing media, pundits such as Trish Regan and websites like the Gateway Pundit decried the decision and accused Twitter of bias. The furor quickly spread through dozens of Facebook groups, Reddit forums and YouTube videos.
The activity was payback for Twitter, Mr. Trump’s favorite social media platform, after the company took action on the president’s tweets for the first time. While for years Twitter had been hands-off on Mr. Trump’s posts, which have often included falsehoods and threats, it added fact-checking labels to two of the president’s messages related to mail-in ballots on Tuesday to signal that they were inaccurate.
That sparked a vitriolic reaction from Mr. Trump, who said on Twitter that the company was interfering with the presidential election and stifling free speech. His supporters — a mixture of mainstream Republicans, far-right personalities and online acolytes — then quickly turned to a well-worn playbook of vilifying those whom they saw as slighting him.
But this time, the right-wing machinery training its sights on a publicly traded company — Twitter — and its roughly 5,000 employees, took on an added menace, disinformation researchers said.
The tactics are something that Mr. Trump’s supporters “return to again and again,” said Melissa Ryan, chief executive of Card Strategies, a consulting firm that researches disinformation. “Where it gets worrisome for the tech companies is, of course, the Trump administration has the power to make their life very difficult.”
On Wednesday, Mr. Trump continued his tirade. In two tweets, he accused social media companies of working to “totally silence conservatives voices.” He added, “We will strongly regulate, or close them down, before we can ever allow this to happen.”
The right-wing backlash against Twitter built even as some researchers questioned how effective the labels on Mr. Trump’s tweets would be. Some said they were unlikely to sway public opinion about the reliability of Mr. Trump’s statements; others criticized the “get the facts” language that Twitter had added to the posts as vague. Several pointed out that Twitter had not gone as far as removing the posts.
Even labeling a claim “false” on social media reduced its perceived accuracy by only about 13 percentage points, said Katie Clayton, a researcher who worked on a 2019 study at Dartmouth College that examined fact-check labels on news headlines on Facebook.
Still, she said, Twitter’s actions were “a step in the right direction.”
A Twitter spokesman said the online harassment that one of its executives was experiencing was “disappointing.” The San Francisco company, whose employees curated its fact-checks, added that it would continue labeling tweets that contained misinformation about elections or coronavirus. It said it might expand those policies to include labels for misinformation about additional topics.
In total, the backlash against Twitter has spread to more than 100 Facebook group and pages, thousands of tweets and several Reddit forums in which Mr. Trump’s followers have claimed that Twitter suppresses conservative speech, according to a New York Times analysis. In those online threads, Trump supporters said Twitter employees were biased liberals and urged Mr. Trump to fast-track regulations to limit the company.
“I wonder if Jack Dorsey grew up dreaming: ‘one day I will connect the world with an easy to use app, giving every individual a voice, then I will censor, throttle, and ban the people with whom I disagree,’” wrote one Twitter user, referring to the social network’s chief executive.
Fans of Mr. Trump also rapidly turned on Yoel Roth, a Twitter executive who combats bots, election interference and fake accounts. The campaign against Mr. Roth started late Tuesday when Liz Wheeler, a TV host on One America News Network, a cable network that has championed the Trump administration’s agenda, unearthed and reposted tweets in which Mr. Roth had referred to Mr. Trump as a “racist tangerine.” Others added a tweet from Mr. Roth that called Senate majority leader Mitch McConnell, a Republican from Kentucky, a “bag of farts.”
Far-right media outlets like Breitbart and The Gateway Pundit immediately seized on the messages as proof that Twitter was biased against conservatives. By Wednesday morning, Mr. Roth’s old tweets had reached the White House. On Fox News, Kellyanne Conway referenced him by name and called on supporters to “wake him up.”
“I think I want to raise the name of somebody at Twitter,” Ms. Conway said in the interview, spelling out Mr. Roth’s Twitter handle so that viewers could find his social media profile. “Somebody in San Francisco, go wake him up and tell him he’s about to get a lot more followers.”
Mentions of Mr. Roth on Twitter spiked to 180 mentions in a five-minute span on Tuesday evening, and to 478 mentions on Wednesday morning, according to The Times analysis. Mr. Roth declined to comment.
The decision to fact-check Mr. Trump was not Mr. Roth’s, a Twitter spokesman said. It was instead made by executives focused on legal and policy issues after Mr. Trump’s tweets were reported to the company through a portal used by election-related nonprofits and those who administer elections in states.
In Washington, the confrontation between Mr. Trump and Twitter reinvigorated calls among Republican lawmakers to change Section 230 of the Communications Decency Act, which protects technology companies from most liability for content posted by their users.
“The law still protects social media companies like Twitter because they are considered forums not publishers,” Mr. Rubio tweeted on Tuesday. “But if they have now decided to exercise an editorial role like a publisher then they should no longer be shielded from liability & treated as publishers under the law.”
In a letter on Wednesday to Mr. Dorsey, Mr. Hawley said Twitter enjoyed a “special immunity worth billions” and called on lawmakers to put an end to the “sweetheart deal.”
Ms. Ryan, the disinformation researcher, said Twitter is in “uncharted territory.”
“You can predict pretty easily how Trump is going to respond,” she said. But with Twitter, “once the company enforces a policy, is it going to succumb to the blowback? Or is it going to stay the course? I think that’s the important thing to watch moving forward.”
Kate Conger reported from Oakland, Calif., and Davey Alba from New York. Ben Decker contributed reporting.