WASHINGTON — Four years ago, President Donald Trump used his bully pulpit to spread lies about the election, leading his supporters to act on their belief in mass voter fraud and eventually attack the U.S. Capitol.

With days to go before the 2024 election, Trump and his allies are running a similar playbook, priming his voters to believe the election may be “rigged.”

In addition to domestic disinformation campaigns, foreign government influence operations, overseas terrorist groups and domestic extremists are all simultaneously trying to exploit the election for their own gain, according to dozens of pages of law enforcement documents and months of reporting by NBC News.

“We’ve been describing the threat environment as everything, everywhere, all at once,” the New York Police Department’s deputy commissioner for intelligence and counterterrorism, Rebecca Weiner, said in an interview, describing the overall threat environment.

One major difference this time is that a Democrat is in the White House, and federal authorities, including the FBI and the broader Justice Department, have spent years trying to learn from their mistakes the last time around while arresting and prosecuting more than 1,500 Trump supporters for the Jan. 6 Capitol attack. They, along with the Cybersecurity and Infrastructure Security Agency — no longer a target of the sitting president — are already preparing to respond to attempts at election interference, both foreign and domestic.

But federal authorities also caution that their role is limited by law and by typical practice, noting that state and local officials, not the federal government, are the primary authorities on elections. The Justice Department also, by policy, has a “quiet period” leading up to Election Day when it avoids taking public actions that could be seen to have an impact on an election. And the Justice Department may be hesitant to do anything that could be construed as political given the extreme politicization of the country in 2024 and years of accusations from Republicans that it is “weaponized” against Trump.

Attorney General Merrick Garland theoretically could use his own bully pulpit to push back against conspiracy theories about mass voter fraud once the quiet period ends after Tuesday or after the election is called, a process that could extend for days, even weeks. Yet, as 2020 showed, election lies can spread so quickly online that even media outlets will have trouble reporting out the facts in a timely manner. Moreover, Trump and his allies have spent the past decade undermining public trust in the Justice Department and the FBI, diminishing the rhetorical power of those institutions.

“There’s no white knight coming,” a federal law enforcement official told NBC News, speaking on the condition of anonymity to describe the posture of federal authorities in the coming weeks, after Election Day.

The Justice Department and the FBI will be focused primarily on evaluating violations of federal law, with the Justice Department saying in a statement that it has an important role to play in “deterring and combatting discrimination and intimidation at the polls, threats of violence directed at election officials and poll workers, and election fraud.”

But they are not going to position themselves in a fact-checking role that could quickly become political fodder. Even if federal authorities investigate an allegation and find it to have no merit, it would not be standard practice to announce it publicly, as the Justice Department’s regular practice is to speak through criminal charges, not publicly discuss uncharged conduct.

Law enforcement officials across the country said they believe the 2024 election will have a more sustained drumbeat of partisan rhetoric and disinformation than the 2020 election. If the race is too close to call for days or longer, the potential for threats of violence and actual violence will steadily grow.

Until electors formally cast their votes for president and vice president in state capitols nationwide on Dec. 17, multiple groups in the U.S. and abroad will try to fill the information vacuum with threatening rhetoric and disinformation, the officials said.

Law enforcement officials expect the windows for potential violence to be compressed. Instead of growing over weeks and months, as they did in 2020, threats of violence could flare intermittently as the votes are counted and the results are certified in the days to weeks after Tuesday.

While no direct threat has emerged thus far given that the results have not come in, angry mobs popped up quickly online in the aftermath of the election in 2020, when right-wing organizers could quickly summon people to locations with false claims and conspiracy theories. The FBI and the Department of Homeland Security have already warned in a joint intelligence bulletin that domestic extremists who believe in election-related conspiracy theories are the most likely threat of election-related violence.

Still, the prospect of another Jan. 6 appears unlikely. Security at the Capitol has increased dramatically, with Jan. 6 itself — the day Congress meets to formally count the electoral votes — being designated as a National Special Security Event, which brings more resources. Much of the leadership of right-wing extremist groups who helped organize for the Capitol attack are also in prison for their actions on that day. Follow-up events have attracted light crowds as other Trump supporters worry, based on unfounded internet conspiracy theories, that the FBI might be setting them up.

Millions of voters still believe Trump’s lies about the 2020 election, and the likely threat landscape, as federal authorities see it, is much more likely to involve individual actors — “lone wolves” or small groups who could target polling places and state and local government buildings.

Despite their limitations, federal authorities have taken steps to prepare. The Justice Department has created an Election Threats Task Force, which has focused on prosecutions of people who threaten elections officials, to combat an extraordinary threat environment for election workers across the county.

Garland said in a recent statement that the Justice Department’s “warning remains clear: Anyone who illegally threatens an election worker, official, or volunteer will face the consequences,” and the Justice Department will continue to aggressively investigate and prosecute anyone who threatens elections officials in the chaotic weeks ahead.

“For our democracy to function, Americans who serve the public must be able to do their jobs without fearing for their lives,” he said.

The FBI has also set up a National Election Command Post at headquarters specifically to focus on election threats, as is standard practice in an election year. It has held trainings and mock drills and has been monitoring the country for threats of potential violence, as well as social media threats and foreign interference.

“The command post will track status reports and significant complaints from FBI field offices; monitor for indicators of criminal efforts to disrupt the election process; identify trends; and provide guidance to FBI field offices,” the FBI said in a statement. “In addition, the command post will coordinate any FBI response to any election-related incident.”

Federal, state and local law enforcement agencies have been involved in a series of more than 200 tabletop exercises and training operations over the last two years in anticipation of potential Election Day and post-Election Day scenarios — including active shooters or bomb threats. U.S. officials said there are plans and processes to deal with myriad potential threats and other issues. One official pointed to recent fires set with incendiary devices at ballot drop boxes in the Northwest, noting that the incidents are under investigation and that potentially affected voters have been given options to fill out replacement ballots.

Two law enforcement officials expressed some concern that a federal response to any serious election issues could be chaotic and involve a “hodgepodge” of different state, local and federal law enforcement agencies and local election entities. They worried that communicating clearly and quickly with multiple entities could be challenging in a potentially chaotic or fluid situation.

Four other current and former law enforcement sources said they worried that disinformation and conspiracy theories could affect some segments of the law enforcement community, especially in parts of the country where Trump has significant support. The issue has come up before. As NBC News has reported, a week after the Jan. 6 attack, a top FBI official was warned that “a sizable percentage” of the bureau’s employees were “sympathetic” to the rioters who stormed the Capitol because of election misinformation.

The Justice Department and the FBI do have a more defined role to play in combating foreign interference in U.S. elections, as illustrated by recent cases federal prosecutors brought against Russian propagandists who paid right-wing, pro-Trump influencers millions of dollars to make videos and by making clear the role that China and Iran are trying to play in the election this year.

Jen Easterly, the director of the Cybersecurity and Infrastructure Security Agency, said that the postelection period is a major focus of foreign adversaries, including Russia, China and Iran, and that America’s “foreign adversaries understand that that period of uncertainty and ambiguity is one where they can slip into to incite Americans against each other, to potentially incite violence, to stoke discord, to undermine American confidence and legitimacy of the vote.”

A Justice Department official said there are many ongoing investigations into potential violations of election law. The official expects robust investigative and prosecutorial actions in the period after the election for anything that meets the legal threshold.

There will certainly be incidents and disruptions in next week’s elections, Easterly said, but it is important for Americans to know that those responsible are going to be investigated and held accountable.

“Election officials have been preparing for this for years. They have exercised for it. They have trained for it. We have worked with them directly to deal with all of these incidents and disruptions,” she said. “The process is working.”