A federal judge has indicated that an attempt to stop the far-right Republican congresswoman Marjorie Taylor Greene running for re-election will be allowed to proceed.

The challenge from a group of Georgia voters says Greene should be disqualified under the 14th amendment to the US constitution, because she supported insurrectionists who attacked the US Capitol on 6 January 2021.

A similar challenge in North Carolina, against Madison Cawthorn, another prominent supporter of Donald Trump, was blocked.

But on Friday Amy Totenberg, a federal judge in Georgia, said she had “significant questions and concerns” about the ruling in the Cawthorn case, CNN reported.

Totenberg said she was likely to rule on Greene’s attempt to have her case dismissed on Monday, two days before a scheduled hearing before a state judge.

The 14th amendment was passed by Congress in 1866, a year after the end of the civil war, and ratified in 1868.

It says: “No person shall be a Senator or Representative in Congress, or elector of President and Vice-President, or hold any office, civil or military, under the United States, or under any state, who, having previously taken an oath … to support the Constitution of the United States, shall have engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof.”

Congress can reverse any such prohibition.

In March, the challenge to Cawthorn was shut down by a Trump-appointed judge with reference to a civil war amnesty law passed by Congress in 1872. According to CNN, Totenberg said she thought that law was retroactive and not meant to apply to future insurrectionists.

A bipartisan Senate committee connected seven deaths to the Capitol riot, in which Trump supporters sought to stop certification of Joe Biden’s election victory.

Greene has been widely linked to events on January 6. In one example, an organiser of pro-Trump events in Washington that day told Rolling Stone Greene was among a group of far-right Republicans who coordinated with protesters.

“I remember Marjorie Taylor Greene specifically,” the anonymous source said. “I remember talking to probably close to a dozen other members at one point or another or their staffs.”

A spokesperson for Greene said she and her staff “were focused on the congressional election objection on the House floor and had nothing to do with planning of any protest”.

In the immediate aftermath of the storming of Congress, in the last legalistic gasp of Trump’s attempt to stay in power, 147 Republicans voted to object to results in key states.

Greene has said she does not encourage violence. Her attorney in the Georgia case is James Bopp Jr, who cited the 1872 amnesty law in his successful attempt to have the Cawthorn challenge dismissed.

Like the challenge to Cawthorn, the challenge to Greene is backed by Free Speech for People, a group which seeks election and campaign finance reform.

Responding to the Cawthorn dismissal, Ron Fein, legal director of Free Speech for the People, told the New York Times: “According to this court ruling, the 1872 amnesty law, by a trick of wording – although no one noticed it at the time, or in the 150 years since – completely undermined Congress’s careful decision to write the insurrectionist disqualification clause to apply to future insurrections.

“This is patently absurd.”

In January, Fein told the Guardian his group aimed to set “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”.

He added: “The insurrection threatened our country’s entire democratic system and putting insurrectionists from any state into the halls of Congress threatens the entire country.”

Writing for the Guardian, the Princeton academic Jan-Werner Muller said: “Whether a heavily right-leaning US supreme court will uphold disqualifications is a very open question indeed – but there is every reason to try enforcing them.”