In a telephone call days after the 2020 election, Oath Keepers leader Stewart Rhodes urged followers to go to Washington and fight to keep President Donald Trump in office.

A concerned member of the extremist group began recording because, as he would later tell jurors in the current seditious conspiracy trial of Rhodes and four associates, it sounded as if they were “going to war against the United States government.”

That Oath Keeper contacted the FBI, but his tip was filed away. He was only interviewed after Rhodes' followers stormed the Capitol on Jan. 6, 2021.

The defendants are charged with plotting to stop the transfer of presidential power, and their trial is raising more questions about intelligence failures in the days before the riot that appear to have allowed Rhodes' anti-government group and other extremists to mobilize in plain sight.

“You don't have to have been invited to a secret meeting of the Oath Keepers ... to know that the Oath Keepers presented a threat," said Mike German, a former FBI agent and fellow with the Brennan Center for Justice’s Liberty & National Security Program.

It’s unclear to what extent authorities were tracking Rhodes and his militia group before Jan. 6. But it has since become apparent that authorities had plenty of intelligence warning that some Trump supporters were planning an assault to stop the certification of Democrat Joe Biden’s victory.

Despite that, police left unprepared on the front lines were quickly overwhelmed by the mob that engaged in hand-to-hand combat with officers, smashed windows and poured into the Capitol.

Additional details emerged this month when the House committee investigating the attack disclosed messages showing that the Secret Service was aware of plans for Jan. 6 violence.

Jurors in the Washington trial, which is expected to last several more weeks, have received a trove of evidence from prosecutors. That includes Rhodes' secretly recorded call on Nov. 9, 2020, encrypted messages and surveillance footage from the Virginia hotel where the Oath Keepers stashed weapons for a “quick reaction force" that could quickly run guns into the capital if they were needed.

Much of the evidence, however, has come in the form of statements and writings that Rhodes made publicly in the weeks before Jan. 6. They show how the former U.S. Army paratrooper and Yale Law School graduate was openly broadcasting his desire to overturn the election and threatening possible violence to attain that goal.

Days after the election on Nov. 3, 2020, Rhodes announced on conspiracy theorist Alex Jones’ “Infowars” show that his group was already mobilizing to stop the transfer of power.

“We have men already stationed outside of D.C. as a nuclear option in case they attempt to remove the president illegally, we will step in and stop it,” Rhodes said.

Jurors also watched video of a speech Rhodes gave in December 2020 in Washington, where thousands of Trump supporters came to rally behind the then-president's election lies. Rhodes urged Trump to invoke the Insurrection Act, which gives presidents wide discretion to decide when military force is necessary, to call up a militia and “drop the hammer” on the “traitors.”

“He needs to know from you that you are with him, that if he does not do it now while he is commander in chief, we’re going to have to it ourselves later, in a much more desperate, much more bloody war. Let's get it on now while he is still commander in chief,” Rhodes told the crowd.

That day, Rhodes attracted the attention of a U.S. Capitol Police special agent who was doing counter-surveillance monitoring and had recently read a news article about the group. Rhodes was wearing a black cowboy hat, an eyepatch and an expired congressional badge from when he was a staffer for then-U.S. Rep. Ron Paul in the late 1990s. The agent took a photo and sent it to colleagues. Rhodes was also wearing a black cowboy as he roamed the exterior of the Capitol building as Oath Keepers entered on Jan. 6.

Two weeks before the Capitol riot, Rhodes published an open letter to Trump on the Oath Keepers' website, suggesting that his followers may need to “take to arms" if Trump doesn't act over what he viewed as a stolen election.

Rhodes and his associates are the first Jan. 6 defendants to stand trial on seditious conspiracy charges. On trial with Rhodes are Thomas Caldwell of Berryville, Virginia; Kenneth Harrelson of Titusville, Florida; Jessica Watkins of Woodstock, Ohio; and Kelly Meggs of Dunnellon, Florida.

Abdullah Rasheed, the Oath Keeper member who recorded Rhodes' call on Nov. 9, 2020, told jurors that that he tried to reach out to the FBI and others to share his concerns about Rhodes' rhetoric. When asked whether anyone called him back, Rasheed responded: “Yeah, after it all happened.”

An FBI agent acknowledged on the stand that the bureau first received a tip about the call in November 2020. Pressed by a defense lawyer about why the FBI didn't investigate at the time, another agent said the FBI receives thousands of tips a day. The tip wasn't ignored, but was “filed away for possible future reference," the agent said.

The Nov. 9 call appears to have been to discuss plans for a “Stop the Steal” rally in Washington that would happen days later, not the Jan. 6 insurrection. But Rhodes throughout the meeting repeatedly tells his followers to prepare for violence, instructing them at one point to make sure Trump knows they are “willing to die for this country."

Defense lawyers are not challenging many of the facts in the case, but say prosecutors have twisted the defendants' intent. The lawyers have acknowledged the group had a “quick reaction force” stationed outside of Washington, but say it was a defensive force to be used only in the event of attacks from left-wing antifa activists or if Trump invoked the Insurrection Act.

The defense team has hammered on prosecutors' lack of evidence of any specific plan to attack the Capitol before Jan. 6. Rhodes' lawyers say their client will testify that all his actions were in anticipation of Trump calling up a militia under the Insurrection Act. Trump never did that, but Rhodes' lawyers say what prosecutors have alleged is seditious conspiracy was merely lobbying a president to use a U.S. law.

Prosecutors recently showed jurors jurors a map pointing to where Rhodes made several stops to purchase guns and other gear on his trip from Texas to Washington before the riot. He spent thousands of dollars on weapons, including a AR-rifle, ammunition, sights, mounts and other items, according to records shown to jurors.

Rhodes and the others are not charged with violating gun laws. Authorities have acknowledged there is no evidence that any of the weapons stashed at the Virginia hotel that housed the “quick reaction force” were brought into the District of Columbia.

“So the armed rebellion was unarmed?” defense lawyer James Bright asked an agent.

“The armed rebellion was not over,” the agent responded.