AUGUSTA, Maine — It will take a state constitutional amendment to allow Mainers who vote early to place their ballots directly into a ballot box or voting machine rather than placing an absentee ballot into an envelope that’s sealed until Election Day.

Advocates for that change gathered Wednesday at the State House to urge passage of LD 156, a bill that would trigger a statewide referendum to change language in the Maine Constitution to allow early voting. The bill would require two-thirds majority votes in both chambers of the Legislature.

Early voting, which takes place in 32 other states, differs from in-person absentee ballot voting, which Maine now allows without proof of hardship by the end of a municipality’s business day on the Thursday before Election Day.

Rep. Michael Shaw, D-Standish, sponsor of LD 156, said he expects the Legislature’s Veterans and Legal Affairs Committee, which held a hearing on the bill Wednesday, to make a recommendation on it within the next few weeks. If LD 156 wins legislative approval, Shaw expects the question to go to Maine voters this November.

Shaw’s bill seeks to amend the state constitution, which calls for senators and representatives to be elected “on the Tuesday following the first Monday of November biennially forever,” and for the governor to be elected “on the Tuesday following the first Monday of November every four years.” LD 156 would add a sentence allowing the Legislature to authorize a process that would allow qualified voters to cast ballots “during a period immediately preceding an election.”

The proposal does not specify how soon before Election Day early voting could start. Shaw said details related to early voting rules would be addressed during a future legislative session — if voters approve a constitutional amendment allowing legislators to work on an early voting system for Maine.

The impact on voters would be nuanced, but the change would reduce the administrative strain on municipal clerks caused by recent increases in absentee balloting, advocates say.

With in-person absentee balloting, early voters now complete absentee ballots, which are sealed in envelopes that the voter signs and which are held at a municipal clerk’s office until Election Day, when poll workers place them in ballot boxes or voting machines.

The process of recording, tracking and securing absentee ballots strains municipal clerks’ staffs, according to Waterville City Clerk Patti Dubois, who is chairwoman of the Elections Working Group for the Maine Town and City Clerks’ Association. On Election Day, poll workers must read off the name of each voter who an cast absentee ballots, open the envelopes, unfold the ballots and feed them into voting machines or ballot boxes. The state now allows that process to begin the day before Election Day because, “we physically were unable to get it done within the time allotted,” Dubois said.

Waterville handles between 3,000 and 4,000 in-person absentee ballots during a typical general election, Dubois said. She supports the concept of switching to early voting, with the caveat that municipalities be allowed to opt in or out of early voting based on their circumstances. It would be helpful to larger cities and towns, she said, but smaller municipalities might find it easier to stick with in-person absentee voting.

The Maine Town and City Clerks’ Association is not taking a position on LD 156, according to Tracey Stevens, Freeport’s town clerk and chairwoman of the association’s legislative policy committee.

“We would not want to influence the voting process in any way,” Stevens wrote in an email, noting that municipal clerks would be handling the ballots if LD 156 prompts a statewide referendum.

Among those who spoke in favor of LD 156 and early voting Wednesday were representatives of the League of Women Voters and the American Civil Liberties Union of Maine. John Atwood, who was chairman of a five-person commission that traveled around Maine last fall to solicit public comment on the state’s election system, also spoke Wednesday in favor of early voting, reflecting the commission’s recommendation for the switch.