PORTLAND, Maine — Maine’s top election official could face an impeachment attempt in the state Legislature over her decision to keep President Trump off the Republican primary ballot.

At least one Republican lawmaker has vowed to pursue impeachment against the Democratic secretary of state, Shenna Bellows, despite long odds in the Democratic-controlled Legislature.

Mr. Bellows said Friday that she had no comment on the impeachment effort, but said she was duty-bound by state law to make a determination on three challenges brought by registered Maine voters. She reiterated that she suspended her decision pending an anticipated appeal by Mr. Trump in Superior Court.

“Under Maine law, I have not only the authority but the obligation to act,” she said. “I will follow the Constitution and the rule of law as directed by the courts,” she added.

Ms.Bellows’ decision Thursday followed a ruling earlier this month by the Colorado Supreme Court that removed Mr. Trump from the ballot under Section 3 of the 14th Amendment. That decision is on hold until the Supreme Court decides whether Mr. Trump violated the Civil War-era provision prohibiting those who “engaged in insurrection” from holding office.

“In 150 years, no candidate was kept off a ballot for engaging in an insurrection. It’s now happened twice to Donald Trump in the last two weeks. There will be major pressure on the Supreme Court to offer clarity very soon,” a Notre Dame Law School professor and election law scholar, Derek Muller, said.

In Maine, a state representative, John Andrews, who sits on the Veterans and Legal Affairs Committee, called the decision “hyper-partisanship on full display” as he pressed for an impeachment proceeding. He said he sent a notice to the state revisor’s office for a joint order to set the wheels in motion ahead of lawmakers’ return to Augusta next week.

“There is bipartisan opposition to the extreme decision made by the secretary of state. She has clearly overstepped her authority. It remains to be seen if her effort at voter suppression will garner enough Democrat support to remove her from her position,” said the state House Republican leader, Billy Bob Faulkingham.

The decision exposed Ms. Bellows to hate and vitriol on social media — along with posts showing support — and her office said Ms. Bellows and members of her staff were subjected to threats, something she called “unacceptable.”

“My obligation is to the Constitution and the rule of law. It’s the Constitution and the rule of law that make our Democratic Republic so great. No one should be threatened for doing their job,” she said Friday evening.

“I hope those people who are engaging in angry and threatening communications consider the impact of their words and actions,” she added.

Among Maine’s congressional delegation, only a Democratic Representative, Chellie Pingree, who represents the liberal 1st Congressional District, supported Ms. Bellows’ conclusion that Mr. Trump incited an insurrection, justifying his removal from the March 5 primary ballot.

Senator King, an independent who caucuses with Democrats, said Friday that absent a final judicial determination on the issue of insurrection, the decision on whether Mr. Trump should be considered for president “should rest with the people as expressed in free and fair elections.”

Representative Jared Golden, a Democrat representing the 2nd Congressional District, agreed that “until (Trump) is found guilty of the crime of insurrection, he should be allowed on the ballot.”

Senator Collins, the state’s senior senator, was one of a handful of Republicans to vote to convict Trump during his second impeachment trial, and she criticized him in a floor speech for failing to obey his oath of office.

But she nonetheless disagreed with Ms. Bellows’ decision. “Maine voters should decide who wins the election, not a secretary of state chosen by the Legislature,” she said.