A longshot legal bid to disqualify and remove Donald Trump from the 2024 US presidential ballot has been gaining traction.

Initially heralded by liberal activists, the theory has burst to the fore in recent weeks as prominent conservatives embrace the effort.

But critics warn that, if it moves forward, it risks robbing voters of the right to deliver their own verdict on whether the former president should return to the White House.

The untested legal gambit Is a last-ditch bid of sorts against an ex-president who remains popular with his base. Its ultimate arbiter could be the conservative Supreme Court he helped shape – if it even gets that far.

On Wednesday, a Washington-based watchdog group sued to block Mr Trump from the Republican primary in the state of Colorado – likely the first of several lawsuits of its kind.

The Trump campaign quickly shot back that the legal challenge is “stretching the law beyond recognition” and has no basis “except in the minds of those who are pushing it”.

“Joe Biden, Democrats, and Never Trumpers are scared to death because they see polls showing President Trump winning in the general election,” spokesman Steven Cheung told the BBC’s US partner CBS News.

Despite his mounting legal troubles, Mr Trump remains the dominant frontrunner for the Republican nomination and is polling neck-and-neck with President Joe Biden ahead of their expected rematch.

The strategy to bar him from the primary ballot invokes a rarely used provision of the US Constitution – Section Three of the 14^th Amendment – that bars those who have “engaged in insurrection or rebellion” against the country from holding federal office.

The 14th Amendment was ratified after the Civil War, and Section 3 was deployed to bar secessionists from returning to previous government posts once southern states re-joined the Union.

It was used against people like Confederate president Jefferson Davis and his vice-president Alexander Stephens, both of whom had served in Congress, but it has seldom been invoked since.

Yet it has re-emerged as a political flashpoint in the wake of Mr Trump’s sprawling effort to overturn his 2020 election defeat, which culminated in the riot at the US Capitol in January 2021.

In the attack’s aftermath, the US House of Representatives impeached the then-president on a charge of “incitement of insurrection”.

Had the US Senate voted to convict him on that charge, it would have had the option to take a second, simple-majority vote to bar him from ever serving in office again, on the basis of the 14^th Amendment.

But that never happened: the Senate failed to reach the two-thirds majority required to convict Mr Trump, so the second vote never happened.

Two and a half years later, with Mr Trump’s third bid for the presidency remarkably buoyant, the 14^th Amendment is once again the talk of Washington.

At the vanguard of the effort is Free Speech For People, a self-described non-partisan advocacy group that last year filed challenges against Trump-backing lawmakers it labelled “insurrectionists”.

The 14th Amendment was not written solely to apply to the post-Civil War era, but also to future insurrections, argues Ron Fein, the organisation’s legal director.

He told the BBC the US Capitol riot succeeded “in delaying the peaceful transfer of power for the first time in our nation’s history, which is further than the Confederates ever got”.

“The particular candidates we challenged in 2022 had participated or assisted in the efforts that led up to the insurrection,” Mr Fein said.

And, he added, their cases established important legal precedents that can be applied to show “Trump is the chief insurrectionist”.

Free Speech For People intends to seek disqualification in multiple states. It is also separately petitioning the top election officials in at least nine states to unilaterally excise Mr Trump from the primary ballot.

Either move will inevitably draw an objection from the candidate himself, triggering a process that could ultimately place his fate in the hands of the US Supreme Court.

The legal strategy has picked up considerable steam since August, when Mr Trump was accused of election subversion in two separate criminal cases.

That same month, conservative legal scholars William Baude and Michael Stokes Paulsen wrote in a law review paper that Section 3 is “self-executing, operating as an immediate disqualification from office, without the need for additional action by Congress”.

Mr Trump could therefore be rendered ineligible for the ballot “by every official, state or federal, who judges qualifications”, the pair concluded.

Mr Baude and Mr Paulsen are members of the Federalist Society, a highly influential, conservative advocacy group.

They adhere to the view that the Constitution must be interpreted as its authors intended at the time, and their stance has since been backed by other legal experts with conservative credentials.

Even the Supreme Court, with its conservative majority and trio of Trump-appointed judges, may be receptive to their argument, said Jeffrey Sonnenfeld, a dean at the Yale School of Management who supports the Baude-Paulsen perspective.

“All that is needed is that one of 50 state election officials has to find him ineligible,” he told the BBC.

“Just one will send it to a state court review, which will be appealed by either side and sent to the US Supreme Court for a speedy resolution.”

With voters heading to the polls early next year, the case will be decided quickly, he predicted.

But the effort is not without its detractors, who question the theory’s viability and whether it should even be implemented in a highly partisan America.

In an opinion piece for Bloomberg, liberal professor Noah Feldman wrote: “Donald Trump is manifestly unfit to be president. But it’s up to voters to block him. Magic words from the past won’t save us.”

“To make a tortured legalistic logic to try to stop people from voting for who they want to vote for is a Soviet-style, banana republic argument,” said New Hampshire Republican Party chairman Chris Ager.

“I’m not a Trump supporter. I’m neutral. But this whole attempt is bad for the country.”

Even Brad Raffensperger, the top elections official in Georgia and a target of Mr Trump’s ire, rejected the move as “merely the newest way of attempting to short-circuit the ballot box”.

But at least two of his counterparts elsewhere have said the matter is under consideration.

Michigan Secretary of State Jocelyn Benson, a Democrat, told MSNBC she was “taking it seriously” and would confer with colleagues in other key states like Pennsylvania and Georgia.

And in a joint statement last week, New Hampshire’s attorney general and secretary of state – both Republicans – said they were “carefully reviewing the legal issues involved”.

The latter is particularly notable, as their state holds the distinction of being the first in the nation to vote in the Republican primary.

The New Hampshire challenge is notably being touted by Bryant “Corky” Messner, a top Republican attorney who ran for the US Senate in 2020 with Mr Trump’s endorsement.

Mr Messner, who intends to finance any 14^th Amendment challenges to Mr Trump in his state, wants the courts to deliver their verdict before he can decide on whether to support Mr Trump.

“To me, it’s purely about the Constitution,” he said. “The US Constitution is more important than any one individual, be it Donald Trump or anyone else.”

“If he ends up being the nominee of the Republican Party and he’s not disqualified, I’ll vote for him.” (BBC)

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