WASHINGTON — The upcoming midterm elections are emerging as a rallying point for domestic extremists and foreign adversaries seeking to disrupt the U.S. and incite violence, the Department of Homeland Security warned Monday.

Unsubstantiated fraud claims, which have haunted the country since the 2020 presidential election, may be used to fuel unrest and doubts about the elections to decide control of Congress, DHS officials said as the agency issued a new national terrorism advisory.

A senior DHS official, speaking on condition of anonymity to discuss the terrorism advisory before its release, told reporters that part of their objective may be to sow discord and undermine credibility in democratic institutions by promoting misinformation about upcoming races.

Concerns about the election is just one element in a terrorism alert that broadly warns of potential violence in what the government calls a “heightened threat environment” that includes foreign and domestic misinformation campaigns, conspiracy theories and lone actors with grievances rooted in racial and ethnic hatred.

The National Terrorism Advisory System Bulletin, which is periodically updated by DHS in a replacement of the color-coded warnings of the past, warns that the primary threat to the U.S. remains lone offenders or small cells of individuals.

It cited as recent examples the attack on the synagogue in Colleyville, Texas, last month by a British national demanding the release of a Pakistani neuroscientist convicted of trying to kill U.S. Army officers, and last week’s bomb threats targeting several historically Black universities.

“DHS remains committed to proactively sharing timely information and intelligence about the evolving threat environment with the American public,” DHS Secretary Alejandro Mayorkas said in a statement. “We also remain committed to working with our partners across every level of government and in the private sector to prevent all forms of terrorism and targeted violence, and to support law enforcement efforts to keep our communities safe.”

U.S. terrorism advisories typically reflect recent events as well as anything on the horizon that might inspire an attack. The concern about the midterms comes as many Americans already are skeptical about the results of the November 2020 election because of the repeated unfounded claims of fraud leveled by former President Trump and his allies.

The alert warns that the months leading up to the midterms could see extremists using online forums and other methods to call for violence at democratic institutions, candidates, party offices, election and poll workers.

“The best way to resist such efforts is to recognize them for what they are: efforts to weaken the fabric of American society,” said Thomas Warrick, a former senior DHS official who is now with the Atlantic Council. “More will be coming as the United States heads towards the Nov. 8, 2022, election.”

The senior DHS official who spoke to reporters Monday singled out only Russia among foreign adversaries, without offering any specific evidence but citing the country’s ongoing efforts to use propaganda and misinformation to undermine the U.S. government long before the standoff over Ukraine.