AUGUSTA — Maine Gov. Paul LePage hopes to turn the state’s ethics panel into a truth squad that checks the veracity of claims made by politicians, but the bill’s prospects of becoming law appeared dim Wednesday as opponents warned it could violate the First Amendment’s protection of free speech.

The plan directs the Maine Commission on Governmental Ethics and Election Practices to investigate campaign claims following a complaint by a candidate for governor or state Legislature. The panel would have to make a public statement if the claim is deemed false.

Backers of the effort, which LePage’s office says is the governor’s “attempt to bring civility to the process,” told lawmakers that having such a check in place will encourage candidates to make fewer false claims about their opponents in advertisements or on the campaign trail.

“Should there be no restraint, no limit or no consequence for lying?” said Sen. Douglas Thomas, a Republican from Ripley who’s sponsoring the bill for the governor. “There should be a mechanism to at least shame those who are behind some of the more outrageous statements.”

But the American Civil Liberties Union of Maine said the proposal violates the constitution, arguing that courts have found that even false statements deserve First Amendment protection. The group asked lawmakers not to turn the ethics panel into the “truth police.”

“We agree that it is unfortunate that when politicians, business leaders and anyone else attempts to deliberately mislead the public, but it’s a much greater threat to our democracy to have the government presume to decide for the public what is truth and what is falsehood,” said Oamshri Amarasingham, public policy counsel for the organization.

The commission’s executive director, Jonathan Wayne, similarly questioned the legality of the proposal, saying it’s “close to the line constitutionally” and urged the Veterans and Legal Affairs Committee to seek advice from the attorney general’s office.

Wayne, who is remaining neutral on the proposal, said the new responsibilities would likely mean less time for the commission’s six employees to carry out their current tasks, like monitoring how people are spending money to influence elections.

LePage’s office said it believes that the lack of penalties if a claim is deemed false — besides a public statement from the commission — would allow the proposal to stand up constitutionally.

But some lawmakers said while they appreciated the idea of encouraging truthfulness in campaigns, they feared the proposal could have unintended consequences, like candidates using the process for their own political gain.