Maine's top election official has ruled that Donald Trump cannot run for president next year in the state, citing a constitutional insurrection clause.
Secretary of State Shenna Bellows said Mr Trump was not eligible because of his actions leading up to the US Capitol riot in 2021.
Maine now joins Colorado as the two states to ban Mr Trump from the ballot.
The decisions increase pressure on the Supreme Court to weigh in.
Colorado votes reliably Democratic, however, Maine is more politically competitive and would be more significant for Mr Trump - the Republican frontrunner - to lose.
The 34-page ruling says that Mr Trump must be removed from the Maine ballot because of the 14th Amendment to the US Constitution - which bans anyone from holding office that has "engaged in insurrection or rebellion".
In her order, Mrs Bellows says that Mr Trump "over the course of several months and culminating on January 6, 2021, used a false narrative of election fraud to inflame his supporters and direct them to the Capitol".
She added that his "occasional requests that rioters be peaceful and support law enforcement do not immunize his actions".
Speaking with BBC News, Mrs Bellows said it was her duty to uphold election laws in her state, and that she hoped the "Supreme Court will settle this matter nationwide".
"I'm mindful that no secretary of state has ever deprived a presidential candidate of ballot access based on section three of the 14th Amendment. But I'm also mindful that no presidential candidate has, ever before, engaged in insurrection."
Mr Trump's campaign had previously called for Mrs Bellows to recuse herself from the process, and on Thursday swiftly criticised her decision.
Campaign spokesman Steven Cheung called Mrs Bellows "a hyper-partisan Biden-supporting Democrat" and claimed she was engaging in "election interference".
He added that the campaign will "quickly file a legal objection in state court to prevent this atrocious decision in Maine from taking effect".
Mr Trump's 2024 presidential candidacy has been challenged in multiple states, on the grounds that the 14th Amendment bans him from holding office.
The 14th amendment was ratified after the American Civil War in order to block Confederate secessionists from returning to power after southern states re-joined the Union.
Colorado's ban was the first instance of the Constitution being used to disqualify a presidential candidate.
But legal experts say the Colorado ruling will have a tough time standing up when it reaches the conservative-leaning US Supreme Court.
And state courts in Michigan and Minnesota have also recently dismissed efforts to block Mr Trump from the ballot.
The case to remove him in the New England state was brought by a handful of former Maine lawmakers who argued that the former president had violated his oath of office.
Former federal prosecutor Joe Moreno told BBC News he believed there was "no way this holds up".
"It's breathtakingly arrogant for her to unilaterally decide that someone has committed insurrection," Moreno said about Mrs Bellows' ruling.
"This will create a political furore… that's the unfortunate outcome here," he said, adding he found Maine and Colorado to be "very shaky legal decisions".
It all leads to a Supreme Court showdown - which Mr Moreno said should take place "rapidly" to stop more states from individually determining Trump's eligibility.
Thursday's ruling is the latest in a growing list of legal woes Mr Trump faces.
He also has upcoming trials in federal court and in the state of Georgia for his alleged efforts to overturn his 2020 loss to Democrat Joe Biden.
But he had not been charged with inciting insurrection in either case.
BBC