Last week, a political action committee called the American Principles Project unveiled a new video on Twitter falsely claiming that Democratic presidential nominee Joseph R. Biden Jr. supported sex changes for 8-year-olds.
Since Friday, a similar video has also appeared on Facebook as many as 100,000 times — primarily in Michigan, a swing state in the Nov. 3 election.
What has been harder to pinpoint is how widely the video has been spreading through text messages.
Though companies like Facebook and Twitter have developed tools for tracking and policing disinformation on their social networks, texting activity is largely a free-for-all that receives little scrutiny from tech companies and government regulators.
“There is no way to audit this,” said Jacob Gursky, a research associate at the University of Texas at Austin. “Organizations are just collecting cellphone numbers from data brokers and mass-texting people.”
The video circulated in Michigan, Wisconsin and Pennsylvania as part of a coordinated texting campaign, according to a study by researchers at the University of Texas at Austin. Over the weekend, it reached a reporter who covers online disinformation for the news site Protocol. The reporter had a Pennsylvania cellphone number.
Twisting the meaning of Mr. Biden’s statements during a recent “town hall” event — which condemned discrimination against children who identify as transgender but did not address sex changes — the campaign was a high-profile example of increasingly widespread efforts to distribute disinformation through text messages.
“During a recent town hall, Joe Biden endorsed giving 8- to 10-year-olds sex change treatments,” the texts read. “This is way too extreme for me. I can’t support him.”
The texts tracked by Mr. Gursky and his fellow researchers said they were sent by the American Principles Project, but they referred to the organization only as “the APP PAC.” The texts purport to arrive from a “Democratic volunteer.”
The American Principles Project did not respond to a request for comment.
Data on texting campaigns is hard to come by. But Robokiller, a company that blocks automated phone calls and texts, said Americans received 2.6 billion political text messages in September, a 400 percent increase since June. The company estimated that since June, Republication-affiliated organizations have sent roughly six times more messages than their Democratic counterparts.
The Texas researchers said texting campaigns are in part a reaction to increased scrutiny on social media services. As Facebook and Twitter have pushed disinformation networks off their services, the networks have resurfaced on private texting apps like Signal, Telegram and WhatsApp, where they can continue operate without being monitored.
Private disinformation networks are prevalent in places like India and Mexico, the researchers said. But they are becoming more common in certain parts of the United States, such as southern Florida, where apps like WhatsApp are popular.