A group of North Carolina voters told state officials on Monday that they want Republican congressman Madison Cawthorn to be disqualified as a congressional candidate, citing his involvement in the 6 January attack on the Capitol.

Cawthorn questioned the outcome of the presidential election during the “Save America Rally” before the Capitol riot later that day that resulted in five deaths.

At the rally, Cawthorn made baseless claims that the election had been stolen from Donald Trump, and has been accused of firing up the crowd, many of whom went on to storm the Capitol.

Lawyers filed the candidacy challenge on behalf of 11 voters with North Carolina’s board of elections, which oversees a process by which candidate qualifications are scrutinized.

The voters say Cawthorn, who formally filed as a candidate last month, cannot run because he fails to comply with an amendment in the constitution ratified shortly after the civil war.

The 1868 amendment says no one can serve in Congress “who, having previously taken an oath, as a member of Congress … to support the constitution of the United States, shall have engaged in insurrection or rebellion against the same”.

The written challenge says the events on 6 January “amounted to an insurrection”, and that Cawthorn’s speech at the rally supporting Trump, his other comments, and information in published reports, provide a “reasonable suspicion or belief” that he helped facilitate the insurrection and is thus disqualified.

“Challengers have reasonable suspicion that Representative Cawthorn was involved in efforts to intimidate Congress and the Vice-President into rejecting valid electoral votes and subvert the essential constitutional function of an orderly and peaceful transition of power,” the complaint read.

The complaint went on to detail the ways Cawthorn allegedly promoted the demonstration ahead of time, including him tweeting: “The future of this republic hinges on the actions of a solitary few … It’s time to fight.” The complaint also details reports of Cawthorn meeting with planners of the 6 January demonstration and possibly the Capitol assault.

Cawthorn, 26, became the youngest member of Congress after his November 2020 election, and has become a social media favorite of Trump supporters. He plans to run in a new district that appears friendlier to Republicans. He formally filed candidacy papers just before filing was suspended while redistricting lawsuits are pending.

Last September, Cawthorn warned North Carolinians of potential “bloodshed” over future elections he claims could “continue to be stolen”, and questioned whether Biden was “dutifully elected”. He advised them to begin amassing ammunition for what he said is likely American-v-American “bloodshed” over unfavorable election results.

“When tyranny becomes law, rebellion becomes your duty,” he said, in addition to describing the rioters who were arrested during the January 6 insurrection as “political prisoners”. He said “we are actively working” on plans for a similar protest in Washington.

Ron Fein, legal director of Free Speech for People, a national election and campaign finance reform group backing the challenge to Cawthorn, told the Guardian the complaint was “the first legal challenge to a candidate’s eligibility under the disqualification clause filed since post civil war reconstruction in the 19th century.”

He said: “It sets a line that says that just as the framers of the 14th amendment wrote and intended, you can’t take an oath to support the constitution and then facilitate an insurrection against the United States while expecting to pursue public office.”

Fein said the challenge will be the first of many against members of Congress associated with the insurrection. Free Speech for People and the group Our Revolution announced last week they would urge state administrators to bar Trump and members of Congress from future ballots.

He said: “This isn’t just about the voters of that district. The insurrection threatened our country’s entire democratic system and putting insurrectionists from any state into the halls of Congress threatens the entire country.”

The challenge asks the board to create a five-member panel from counties within the proposed 13th district to hear the challenge. The panel’s decision can be appealed to the state board and later to court.

The challengers also asked the board to let them question Cawthorn under oath in a deposition before the regional panel convenes, and to subpoena him and others to obtain documents.

John Wallace, a longtime lawyer for Democratic causes in North Carolina, who also filed the challenge, told the Guardian: “The disqualification of Representative Cawthorn certainly should provide a deterrent to others who might try and obstruct or defeat our democratic processes.”

Cawthorn spokesperson Luke Ball said “over 245,000 patriots from western North Carolina elected Congressman Cawthorn to serve them in Washington” – a reference to his November 2020 victory in the current 11th district.

Now “a dozen activists who are comically misinterpreting and twisting the 14th amendment for political gain will not distract him from that service,” Ball wrote.