AUGUSTA — A proposal for Maine to join a group of states hoping to choose U.S. presidents based on the national popular vote appears headed for passage after the House of Representatives enacted the bill by a one-vote margin Tuesday.

More than a dozen states have already joined the popular vote compact, which would only be activated after enough states join to control 270 Electoral College votes, the minimum number needed to win the presidency. If the Maine bill becomes law and the compact gathers the necessary support to take effect, Maine would allocate its four Electoral College votes for president to the winner of the national popular vote regardless of who wins the state.

On Tuesday, the House voted 73-72 to enact the bill. That one-vote margin was narrower than a previous vote of 74-67, when nine people were absent.

The bill now heads back to the Senate, where it is expected to pass after being endorsed in an initial 23-12 vote. Gov. Janet Mills has not said whether she would sign the bill into law.

During a heated debate Tuesday on the House floor, supporters argued that the presidency is a unique national office that should be elected by popular vote, rather than by a handful of swing states that can dominate the Electoral College system. Opponents argued that the compact was an attempt to change the election process without formally amending the U.S. Constitution, and that joining it would silence the voices of rural voters who would be overlooked as candidates focus on winning support in larger cities.

Republicans dominated the nearly hourlong debate, trying to convince wobbly Democrats to reverse course and vote against the proposal.

Opponents argued that Maine already has the “gold standard” for allocating electoral votes, a system they say should be emulated by other states. Maine awards two of its electoral votes to the statewide winner of the presidential election and one each to the winner of each congressional district.

Rep. Laurel Libby, R-Auburn, said the popular vote proposal would silence the voices of voters in Maine’s more rural, conservative 2nd Congressional District.

“The voices that will be silenced in various areas of this state are many – myriad, in fact,” Libby said. “A vote for this motion tells those 90,000-plus Maine voters that their voice doesn’t matter.”

In the last two presidential contests, Donald Trump won one electoral vote from the 2nd Congressional District, while Joe Biden and Hillary Clinton won the other three in 2020 and 2016, respectively.

House Speaker Rachel Talbot Ross, D-Portland, repeatedly interrupted both Libby and House Minority Leader Billy Bob Faulkingham, R-Winter Harbor, for saying the proposal was unconstitutional and would give away Maine’s influence to big cities. Talbot Ross said the arguments were an attack on other representatives and repeatedly warned members not to question the motives or impugn the character of other members.

“Madame speaker, I do not believe it is impugning anyone’s character to say that I feel that is not in line with the Constitution,” Faulkingham said. “That’s how I feel.”

Talbot Ross had to gavel the House back to order when Rep. Joseph Underwood, R-Presque Isle, spoke out of turn and ignored several warnings to stop.

“I do understand that some folks’ definition of impugning character may be different from others,” Libby said, before being interrupted again by Talbot Ross.

“Now you’re questioning the motives of the chair,” Talbot Ross said.

Sponsored by Rep. Arthur Bell, L.D. 1578 would have Maine join an interstate compact with at least 16 other states and Washington, D.C., that have pledged their electoral votes to the winner of the national popular vote. States have committed 205 electoral votes so far.

Two of the last four U.S. presidents, George W. Bush and Donald Trump, won office despite losing the national popular vote. Hillary Clinton earned about 2.9 million more popular votes than Trump in 2016. Al Gore collected 540,000 more votes nationally than Bush in 2000.

House Republicans were unified in opposition Tuesday. Independent Rep. William Pluecker of Warren and Democratic Reps. James Dill of Old Town, Tavis Hasenfus of Readfield, Anne-Marie Mastraccio of Sanford, Karen Montell of Gardiner and Ronald Russell of Verona Island joined Republicans in voting against the bill.

In the Senate, Sen. Craig Hickman, D-Winthrop, broke ranks to oppose the bill, because he worried that it would create an incentive for states to enact policies to suppress Black voters, while bill co-sponsor Rep. Matt Pouliot, R-Augusta, voted in support.

If the Senate affirms its prior support, it will be sent to Gov. Janet Mills, who has not weighed in on the proposal. A spokesperson said after Tuesday’s vote that the governor will decide a course of action when and if the bill reaches her desk.

A similar bill was considered in Maine in 2019. It passed the Senate, but ultimately died in the House.