Looks like the FBI has been public all this time about their ability to do that wrt elections:
https://www.fbi.gov/how-we-can-help-you/safety-resources/sca...
> Intentionally deceiving qualified voters to prevent them from voting is voter suppression—and it is a federal crime.
> However, not all publicly available voting information is accurate, and some is deliberately designed to deceive you to keep you from voting.
Bad actors use various methods to spread disinformation about voting, such as social media platforms, texting, or peer-to-peer messaging applications on smartphones. They may provide misleading information about the time, manner, or place of voting. This can include inaccurate election dates or false claims about voting qualifications or methods, such as false information suggesting that one may vote by text, which is not allowed in any jurisdiction.
> Help defend the right to vote by reporting any suspected instances of voter suppression—especially those received through a private communication channel like texting—to your local FBI field office or at tips.fbi.gov.
So it sounds like they're actively doing this outside of Twitter or social media in general.
IANAL, but here's a Georgetown Law info sheet about how that works, and cites several federal law statues that are applicable:
https://www.law.georgetown.edu/icap/wp-content/uploads/sites...
And a Columbia Law paper that examines the issue in detail:
https://scholarship.law.columbia.edu/cgi/viewcontent.cgi?art...
And also this:
https://news.ycombinator.com/item?id=34026228