U.S. Capitol Police officials said Wednesday they have "obtained intelligence that shows a possible plot to breach the Capitol by an identified militia group on Thursday, March 4" -- the date that far-right conspiracy theorists believe former President Donald Trump will return to power.
The intelligence, which an FBI bulletin said could involve the "Three Percenters" group that prosecutors call extremist, is being taken "seriously," the Capitol Police officials said in a statement posted on Twitter.
"Our Department is working with our local, state, and federal partners to stop any threats to the Capitol. We are taking the intelligence seriously. Due to the sensitive nature of this information, we cannot provide additional details at this time," the statement said.
The Capitol complex remains surrounded with temporary fencing topped with razor wire and some 5,000 National Guard troops remain on site and around the city.
The House changed its schedule Wednesday night so that the chamber will no longer be in session on Thursday, given the security concerns, sources told ABC News.
Democrats had planned a Thursday vote on the George Floyd Justice in Policing Act of 2021, a massive policing reform bill, but now that vote will take place Wednesday night.
The House Sergeant-at-Arms also encouraged staffers to telework through Saturday.
The Senate is still expected to begin debate and votes on the $1.9 trillion coronavirus relief plan on Thursday and hasn't announced any changes to its schedule.
Acting Capitol Police Chief Yogananda Pittman told House lawmakers Wednesday that security around the Capitol complex has been "enhanced" given new concerns about threats to lawmakers and the physical complex over the next few days.
"We are prepared to respond appropriately," Pittman said, but she declined to get into specifics about the threats, saying she would brief lawmakers in private later in the day.
An internal U.S. Capitol Police bulletin distributed Tuesday contains information about a possible militia plot to storm the Capitol on or around March 4, sources told ABC News.
The information in the bulletin is sourced to an FBI intelligence report from late February that describes the an alleged plot by the "Three Percenters militia group to use diversionary tactics such as detonating a bomb" to draw law enforcement away from the Capitol prior to an attempt by the group to take over the U.S. Capitol, according to a law enforcement source.
The credibility of the information in the bulletin remains unclear.
The bulletin describes the Three Percenters' alleged goal of having 50,000 members from around the country travel to D.C. on or around March 4 through March 6 and participate in a plan to overrun law enforcement and the National Guard troops at or near the Capitol Complex, the source said.
Federal prosecutors have described Three Percenters in court as a "militia extremist" group "based on the myth that only three percent of American colonists took up arms against the British during the American Revolution," and that some members "regard the present-day US Government as analogous to the British" during the American Revolution in terms of infringements on civil liberties.
While there are many independent groups that use “Three Percenters” in their name, prosecutors say the term is "representative of a common belief in the notion that a small force with a just cause can overthrow a tyrannical government if armed and prepared."
An FBI spokesperson did not immediately comment on the intelligence information.
One law enforcement source said that initial intelligence does not support a crowd of 50,000 is coming to Washington, D.C., this week.
Sources told ABC News that intelligence chatter surrounding the date of March 4 has been circulating for weeks. The date has significance for adherents to the QAnon conspiracy theory who believe it is the day Trump will return to power. March 4 is also the original date for a presidential inauguration in the Constitution, prior to the ratification of the 20th Amendment in 1933 that changed it to Jan. 20.
How U.S. law enforcement and intelligence agencies missed the violent insurrection on Jan. 6 has been the focus of multiple congressional inquiries in recent weeks.
FBI Director Chris Wray, in testimony Tuesday, told lawmakers how an intelligence information gathered by the FBI in Norfolk, Virginia, warning of possible violence at the Capitol on Jan. 6 was shared with law enforcement partners, including the U.S. Capitol Police on the evening of Jan. 5.
A possible source of the threats is QAnon, the umbrella term for a set of disproven and discredited internet conspiracy theories that allege the world is run by a secret cabal of Satan-worshipping cannibalistic pedophiles. Followers of the fringe movement believe that the 2020 U.S. presidential election was stolen from Trump, who has pushed baseless claims of voter fraud along with his allies.
QAnon followers also believed that Trump would not actually leave office on Inauguration Day but rather would declare martial law, announce mass arrests of Democrats and stop Joe Biden from becoming president. When that didn't happen, the date was moved from Jan. 20 to March 4.
The Federal Bureau of Investigation first labeled QAnon and its fluid online community of supporters as a "dangerous extremist group" in August 2019. A number of individuals believed to be QAnon followers have been charged for their alleged involvement in the deadly insurrection on Jan. 6, when pro-Trump supporters stormed the U.S. Capitol building in Washington, D.C.
On Monday, the U.S. Department of Homeland Security's Office of Intelligence and Analysis issued a confidential assessment to law enforcement agencies, which was obtained by ABC News, saying that the threat of domestic violent extremism in 2020 -- largely driven by "violent anti-government or anti-authority narratives, periods of prolonged civil unrest and conspiracy theories" -- is a trend that will likely continue in 2021 and "could escalate to include targeting of critical infrastructure."
ABC News' Josh Margolin, Benjamin Siegel, Mariam Khan and Trish Turner contributed to this report.