WASHINGTON -- U.S. intelligence and law-enforcement agencies issued another warning about foreign interference -- by Russia, China, Iran, and others -- in the upcoming congressional elections and other elections in the future.

The statement issued on October 19 came less than three weeks before voters cast ballots to choose members of Congress, as well as state governors, state lawmakers, and other elected officials.

The announcement, which was signed by the director of national intelligence, the Department of Homeland Security, the Justice Department, and the FBI, said that "ongoing campaigns" were aimed at undermining confidence in U.S. democracy.

"We are concerned about ongoing campaigns by Russia, China, and other foreign actors, including Iran, to undermine confidence in democratic institutions and influence public sentiment and government policies," the statement said.

"Elements of these campaigns can take many forms, including using social media to amplify divisive issues, sponsoring specific content in English-language media like RT and Sputnik, seeding disinformation through sympathetic spokespersons regarding political candidates, and disseminating foreign propaganda," it said.

The November 6 vote will determine whether the Republicans continue dominating both the House of Representatives and the Senate, or if Democrats will take control.