AUGUSTA — Maine voters are trying to make up their minds about being first in the nation to use a ranked choice system to vote for members of Congress, the Legislature and governor.

A recent Portland Press Herald/Maine Sunday Telegram poll conducted by the University of New Hampshire Survey Center shows that 48 percent of likely voters support the ranked choice method.

However, the poll also found that 23 percent of voters were undecided and 29 percent will vote against the change.

The switch would make Maine the first state to adopt the system, which allows voters to rank candidates by preference instead of choosing a single candidate for each race come Election Day.

The system is used now for Portland’s mayoral and City Council races and has been adopted by other cities in the U.S., but Maine would be the first state to use the system or all statewide elections, including votes for the Legislature, Congress and governor.

The poll, which included more than 500 likely voters and surveyed both mobile and land-line telephones, was conducted in mid-September. The question will appear as Question 5 on the ballot Nov. 8.

Kyle Bailey, the campaign manager for Yes on 5, said the campaign was pleased with the numbers, but noted that other polls suggest stronger support and fewer undecided voters.

“We know there are a lot of undecided voters out there who haven’t heard about this or need more information,” Bailey said.

It’s a point that could be critical to the campaign’s success in 2016, according to Andy Smith, a political scientist and the director of the UNH Survey Center. Smith said with four other ballot questions facing voters, and two of those on the hot-button issues of guns and marijuana, how Mainers vote may not be at the forefront of voters’ minds come November.

“It’s not an issue that most people are very concerned about and it’s certainly not something that people are going to think about very often,” Smith said. He also said the fact that having to explain how ranked choice voting works makes for a difficult sell.

Smith said undecided voters will typically vote no on a question they don’t fully understand. “It’s a very foreign idea and something that’s hard to explain in a short period of time, especially when there are a lot of other things going on, other issues that are more visible or more understandable like legalizing marijuana, for example.”

That’s why the Yes on 5 campaign is focused on informing voters about how ranked choice voting works. If no candidate gets more than 50 percent of the top votes cast after the first tally, the candidate with the fewest first-choice votes is eliminated. Voters who chose the eliminated candidate have their ballots added to the totals of their second-ranked candidate and the ballots are retabulated. This process continues until one candidate has a majority of votes and is declared the winner.

“If your favorite candidate can’t win and no candidate gets an outright majority your vote is not wasted, it counts for the candidate you ranked as your second choice to help us reach a majority winner who is more broadly supported by voters,” Bailey said.

The poll indicates that Republicans are more likely to reject changing Maine’s voting laws with 43 percent or a plurality of those polled saying they would vote against the measure. That compares to 61 percent of Democrats and 45 percent of independents who support the switch.

Younger people surveyed showed higher levels of support for the change, with 51 percent aged 18 to 49 saying they will vote for the switch, while among voters aged 50 and over, only 46 percent saying they favor the change.

Fifty seven percent of voters in households earning less than $30,000 a year supported the proposal, but voters with higher incomes were less enthusiastic. In households earning $30,000 to $60,000, 48 percent supported the measure, while 49 percent supported in households earning more than $60,000.