(DENVER) — After two and a half days of testimony about how former President Donald Trump allegedly played a key role in the violence on Jan. 6 and how that should disqualify him as a future political candidate, Trump’s team has begun mounting their defense in a historic, dayslong hearing in Denver that will wrap up on Friday.

Trump faces a challenge from six Republican and unaffiliated voters in Colorado, represented by the watchdog group Citizens for Responsibility and Ethics in Washington (CREW), who argue that Section 3 of the 14th Amendment bars Trump from the 2024 presidential election.

He and his attorneys have rejected that argument outright.

Over the past few months, efforts to keep Trump from the Republican primary ballot because of the 14th Amendment, which was first enacted after the Civil War, have gained traction in a few states.

A hearing was separately held on Thursday in Minnesota on a similar 14th Amendment complaint against Trump.

Section 3 of the amendment states that someone isn’t eligible for future office if, while they were in office, they took an oath to support the Constitution but then “engaged in insurrection or rebellion against the same, or [gave] aid or comfort to the enemies thereof,” unless they are granted amnesty by a two-thirds vote of Congress.

Supporters of this theory argue it applies to Trump because of his conduct after he lost the 2020 election but sought to reverse the results, including on the morning of Jan. 6, 2021. Trump maintains he did nothing wrong.

Previous such efforts focused on other Republicans have failed, except in New Mexico, where a local commissioner convicted of trespassing at the U.S. Capitol on Jan. 6 was booted from his office.

Among the witnesses that Trump’s attorneys called at the Colorado hearing on Wednesday and Thursday were former Trump administration official Kash Patel, former Trump campaign spokeswoman Katrina Pierson and another organizer of the event near the White House on the morning of Jan. 6, 2021, when then-President Trump addressed supporters shortly before the attack on the U.S. Capitol unfolded.

Texas Republican Rep. Troy Nehls and Michael van der Veen, who represented Trump during his second impeachment trial, will not be witnesses in this case as originally planned.

However, retiring Rep. Ken Buck, a Colorado Republican who has spoken out against 2020 election denialism, will begin testifying later on Thursday.

In his testimony on Wednesday, Patel mostly fielded questions about National Guard resources and operations — including the authorization of the forces, his recollection of correspondence with then-President Trump and local governing bodies about deploying the National Guard and the Department of Defense’s timeline of involvement in and around the events of Jan. 6.

During cross-examination, there were sometimes contentious back-and-forth exchanges between CREW lawyers and Patel over the dates of his National Guard-related meetings with Christopher Miller, who was the acting defense secretary in the final days of the Trump administration.

“A lot was going on…Sue me,” Patel said at one point, to which one of the CREW attorneys responded: “The timing does matter, sir.”

“From my perspective, and my conversation with the secretary of defense and the chairman and secretary of the Army, we had what we needed to initiate under the law … the deployment and activation of the National Guard,” Patel said.

“Did any senior DOJ leader ever state in words or substance that they felt they needed … a different authorization from President Trump before they could deploy National Guard troops to keep the peace on Jan. 6?” Trump’s lawyer asked.

“No,” Patel said.

That testimony rebutted one of the arguments about Trump’s behavior around Jan. 6: that he did not act properly in surging National Guard members.

Miller has previously testified before Congress about the timeline of sending in those forces, which did not arrive to the Capitol on Jan. 6 until nearly 5:30 p.m. — hours after the rioting broke out.

Miller said in 2021 that he was aware of the breach at the Capitol by the time Washington, D.C., Mayor Muriel Bowser called on then-Army Secretary Ryan McCarthy at 1:34 p.m.

Under questioning from lawmakers in 2021, however, Miller admitted that he did not approve an operational plan to deploy the National Guard to the Capitol until 4:32 p.m., more than three hours after he first learned that demonstrators had breached the Capitol perimeter.

Miller testified then that he did not speak with Trump during the attack.

Patel, in his testimony at Trump’s 14th Amendment hearing in Denver, said on Wednesday that none of the delay in deploying the National Guard had anything to do with Trump.

Patel said he still works for Trump — as senior counsel — and is paid $15,000 per month by a Trump-aligned political group.

Katrina Pierson, a spokeswoman for Trump’s 2016 campaign and one of the organizers of the rally on Jan. 6 held at the Ellipse near the White House, testified on Wednesday after Patel and repeated some of what she previously told the House special committee that investigated Jan. 6.

She said she had concerns about fringe right-wing figures, such as Alex Jones, potentially speaking at the Ellipse rally. Ultimately, they weren’t involved.

Pierson also testified to meetings she had with Trump officials in light of her issues with Jones and others.

At one meeting, she spoke with Trump directly, she said, and they touched on broader topics. “I let him know that there were some groups that were going to the Capitol that had been planning to go to the Capitol,” she said.

Trump asked her if they were expecting “trouble,” she said.

“I said, ‘Well, there have been some incidents at some of the previous rallies.’ And he said, ‘Well, we should call the National Guard,'” she testified.

After Pierson, another organizer of the Jan. 6 rally, Amy Kremer, appeared as a witness for Trump on Thursday.

Kremer said that as people were listening to Trump speak at the rally, she “absolutely did not” get the feeling that he was telling people to storm the Capitol — seeking to bolster a main argument of Trump’s attorneys against the 14th Amendment theory.

Scott Gessler, one of Trump’s attorneys, has highlighted how Trump encouraged supporters to protest peacefully at the Capitol during his speech on Jan. 6.

However, during his remarks at the Ellipse, Trump also repeated his baseless allegations that the 2020 election was fraudulent and said, “If you don’t fight like hell, you’re not going to have a country anymore.”

During cross-examination of Kremer’s testimony on Thursday, CREW’s lawyers went through some of her past social media posts and she doubled down on a number of her views on Jan. 6.

“There was no insurrection …. There was a riot,” she said.

Later Thursday morning, Rep. Paul Gosar’s chief of staff, Tom Van Flein, began testifying for Trump. Much of the questioning had to do with his communications with Ali Alexander, a lead organizer of the Jan. 6 rally at the Ellipse.

Tom Bjorklund, the Colorado Republican Party’s treasurer, was the last witness on Thursday morning — and is expected to resume testifying after a break — and he spoke about how he traveled to Washington on Jan. 6, both for the Ellipse event and then to go to the Capitol that day.

Bjorklund has said that he didn’t enter the complex.

Minnesota court also hears 14th Amendment argument

While the Denver hearing continued, the Minnesota Supreme Court, a few states away, heard oral arguments on whether a similar 14th Amendment challenge to Trump should proceed to an evidentiary hearing.

“This is a case of extraordinary importance,” Ron Fein, an attorney for the group Free Speech for People, representing the plaintiffs, said in his opening.

“Section 3 of the 14th Amendment protects the republic from oath-breaking insurrectionists because its framers understood that if they’re allowed back into power, they will do the same or worse. Section 3’s plain text bars Trump from ever holding office,” Fein argued.

Chief Justice Natalie Hudson raised the worrying prospect of chaos at the ballot if different states address the 14th Amendment issue in different ways.

“There could “potentially [be] 50 different states who, depending on the nature of the statutes in those states, [are] deciding this question differently,” she said.

Fein played down the risk from that, contending it was “the way that our constitutional system is set up.”

Nick Nelson, representing Trump, argued in his remarks that when there is a dispute about who is able to be president, “The courts overwhelmingly say that’s not a decision that should be made in the judiciary, that’s a decision that should be made elsewhere.”

Asked by the justices why the court shouldn’t focus on the plain text of Section 3, Nelson said it should be considered in the context of when it was written in the 1800s, after the Civil War.

At one point, Justice Gordon Moore asked Nelson, in his view, what it means to engage in insurrection.

“It doesn’t have to be the Civil War, but that’s the paradigm that we’re working from,” Nelson said. “I would say it’s some sort of organized form of warfare or violence … that is oriented towards breaking away from or overthrowing the United States government.”

When asked about Trump’s impeachment in the wake of Jan. 6, Nelson noted the Republican-led Senate at the time acquitted Trump and said that should be factored into the court’s analysis.

The Minnesota Supreme Court does not have a deadline to make a decision but was urged by the secretary of state’s attorney to do so quickly to ensure a smooth process for the state’s early March primary.

ABC News’ Beatrice Peterson contributed to this report.

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