WASHINGTON — Law enforcement was on high alert Thursday around the U.S. Capitol after intelligence uncovered a "possible plot" by a militia group to storm the iconic building again, two months after a mob of Donald Trump supporters smashed through windows and doors to try to stop Congress from certifying now-President Joe Biden's victory.

The threat appears to be connected to a far-right conspiracy theory, mainly promoted by supporters of QAnon, that former President Trump will rise again to power on March 4 and that thousands will come to Washington, D.C., to try to remove Democrats from office. March 4 was the original presidential inauguration day until 1933, when it was moved to Jan. 20. 

Online chatter identified by authorities included discussions among members of the Three Percenters, an anti-government militia group, concerning possible plots against the Capitol on Thursday, according to two law enforcement officials who were not authorized to speak publicly and spoke on condition of anonymity. Members of the Three Percenters were among the extremists who stormed the Capitol on Jan. 6. 

The threat came as the Capitol police and other law enforcement agencies were taking heat from Congress in contentious hearings this week on their poor handling of the Jan. 6 riot.  Police  were ill-prepared for the mass of Trump supporters in tactical gear, some armed, and it took hours for National Guard reinforcements to come. By then, rioters had broken and smashed their way into the building and roamed the halls for hours, stalling Congress' certification effort temporarily and sending lawmakers into hiding. 

"The United States Capitol Police Department is aware of and prepared for any potential threats towards members of Congress or towards the Capitol complex," Capitol Police said in a statement. 

Lawmakers, congressional staffers and law enforcement officials are still on edge after the attack on Jan. 6, even as the security posture around the Capitol remains at an unprecedented level.

The U.S. House wrapped up its work for the week Wednesday night, but the U.S. Senate still had a busy day scheduled for Thursday with votes going well into the evening. Police beefed up their presence in and around the Capitol. About 5,200 National Guard members remain in D.C., the remainder of the roughly 26,000 that were brought in for President Biden's inauguration that went off with no problems. 

National Guard troops keep watch at the Supreme Court on Capitol Hill in Washington, early Thursday, March 4, 2021, amid intelligence warnings that there is a “possible plot” by a group of militia extremists to take control of the Capitol on March 4 to remove Democrats from power. (AP Photo/J. Scott Applewhite)

There's also a  very large fence around the U.S. Capitol perimeter that walls off all avenues of entry including on the streets around the building, put in place after Jan. 6. And Trump is in Florida. 

Initially it seemed as though the online chatter did not rise to the level of serious concern; an advisory sent earlier this week to members of Congress by Timothy Blodgett, the acting House sergeant-at-arms, said that the Capitol Police had "no indication that groups will travel to Washington D.C. to protest or commit acts of violence."

But that advisory was updated in a note to lawmakers Wednesday morning. Blodgett wrote that the Capitol Police had received "new and concerning information and intelligence indicating additional interest in the Capitol for the dates of March 4th – 6th by a militia group."

Acting Capitol Police Chief Yogananda Pittman said during House testimony Wednesday that her investigators had collected "some concerning intelligence," but declined to provide any details publicly, saying that it was "law enforcement sensitive" and that she would provide a private briefing for the subcommittee members. 

Meanwhile, federal agents looked for any increases in the number of hotel rooms being rented in Washington, as well as monitoring flights to the area, car rental reservations and any buses being chartered to bring groups into the capital, but found nothing significant, a person familiar with the matter told The Associated Press. The person could not publicly discuss details of the security planning and spoke on the condition of anonymity. 

The FBI and Department of Homeland Security also sent a joint intelligence bulletin to local law enforcement officials Tuesday warning that a group of militia extremists had discussed trying to take control of the Capitol on March 4 and encouraging thousands of people to come to D.C. to try to remove Democrats from power.

But there has been a noticeable decline in online activity on some social media platforms surrounding efforts on March 4, and there was already considerably less online chatter than during the lead-up to Jan. 6, a day that Trump repeatedly had promoted for a his rally and encouraged thousands to come to the nation's capital. 

Several QAnon groups still operating on the social media messaging platform Telegram warned followers to stay away from any events on March 4, claiming it was a setup for Trump supporters.

"If there are groups out there planning and advertising events on or around March 4 anywhere in the country (DC included) we strongly urge everyone to avoid them entirely," one Telegram user wrote late last month in a QAnon group that has more than 65,000 followers.

National Guard troops keep watch along Constitution Avenue on Capitol Hill in Washington, early Thursday, March 4, 2021, amid intelligence warnings that there is a “possible plot” by a group of militia extremists to take control of the Capitol on March 4 to remove Democrats from power. (AP Photo/J. Scott Applewhite)

Also, thousands of accounts  that promoted the Jan. 6 event that led to a violent storming of the U.S. Capitol have since been suspended by major tech companies like Facebook and Twitter, making it far more difficult for QAnon and far-right groups to organize a repeat of the mass gathering on Thursday.

Twitter banned more than 70,000 accounts after the riots, while Facebook and Instagram removed posts mentioning "stop the steal," a pro-Trump rallying cry used to mobilize his supporters in January. And the conservative social media platform Parler, which many of Trump's supporters joined to promote false election fraud conspiracy theories and encourage friends to "storm" the Capitol on Jan. 6, was booted off the internet following the siege.

Capitol Police say that they have stepped up security around the Capitol complex since January's insurrection, adding physical security measures such as the fencing topped with razor wire around the Capitol and members of the National Guard who remain at the complex. 

"I think they are definitely prepared for any threats that may come our way in the next couple days," said Rep. Jennifer Wexton, D-Va., who was one of several lawmakers briefed privately by the police. Wexton added that she still questioned the long-term security plan for the Capitol and said Pittman, the acting chief, "has not come up with proactive ways to fix the issues that they had."

So far, about 300 people have been charged  with federal crimes for their roles in the riot. Five people, including a Capitol Police officer, died.

Since his defeat, Trump has been promoting lies that the election was stolen from him through mass voter fraud, even though such claims have been rejected by judges, Republican state officials and Trump's own administration. He was impeached by the House after the Jan. 6 riot on a c harge of incitement of insurrection but was acquitted by the Senate.