Mitt Romney has cut President Obama’s lead in half among Maine voters, although Obama still holds a tough-to-overcome 7-percentage-point advantage, according to a poll conducted last week for the Portland Press Herald/Maine Sunday Telegram.

Obama leads the Republican nominee 49 percent to 42 percent in the statewide telephone survey conducted Tuesday and Wednesday by Portland-based Critical Insights. In mid-September — before the presidential debates sparked enthusiasm for Romney — Obama led by 16 points.

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The race is now close enough in Maine that Romney is winning among men voters for the first time, the poll shows. Strong support among women is keeping Obama in the lead.

Maine is still expected to back Obama overall. Even in the 2nd Congressional District, where Republicans hope to peel off one of Maine’s four electoral votes, Obama appears to have a solid 7-point lead, the poll suggests.

Maine’s same-sex marriage referendum also may be shaping up for a close finish.

Supporters still have a 13-percentage-point lead over opponents — 55 percent to 42 percent, with just 3 percent undecided, according to the poll. However, the lead dropped from 21 points in September, and a tendency for voters to change their votes to “No” in the privacy of the ballot box has experts predicting a much narrower margin on Election Day.

Former Gov. Angus King, meanwhile, appears to have weathered an onslaught of Republican-backed advertising in his race to fill Maine’s open U.S. Senate seat.

King leads Republican Charlie Summers by 16 points — 49 percent to 33 percent, according to the poll. Democrat Cynthia Dill is holding steady with 11 percent support, it says.

Both of Maine’s incumbent members of Congress, Rep. Chellie Pingree, D-1st District, and Rep. Mike Michaud, D-2nd District, are holding large leads in their re-election bids, according to the poll.

Pingree leads Republican Jon Courtney 56 percent to 37 percent, according to the poll. Michaud leads Republican Kevin Raye 55 percent to 36 percent, it says.

Critical Insights conducted the latest poll Oct. 30 and 31 using live telephone interviews of 613 likely voters statewide. The poll has a margin of error of plus or minus 4 percent.

Maine will likely have a big turnout at the polls Tuesday, according to the survey.

Voters said they are paying close attention, especially to the two races that are least predictable: the national presidential race and the state’s marriage referendum.

“There are two things driving people to the ballots — the presidential race and same-sex marriage,” said MaryEllen FitzGerald, president of Critical Insights. “The excitement is really around those two issues.”

THE RACE FOR PRESIDENT

Romney’s gain in the Maine poll reflects a tightening in national polls that show the race virtually tied nationwide.

Pro-Romney enthusiasm grew after his performance in the three presidential debates, especially the first one, according to the Maine poll and others around the country.

In the Maine poll, 40 percent of Romney supporters said the debates had a significant impact on their choice, compared to 24 percent of Obama supporters.

“The first debate clearly made an impact,” said Mark Brewer, associate professor of political science at the University of Maine. “(Voters) thought, ‘You know what? This guy is up for the job. Maybe we should give him a look.’“

Accusations that the White House misled Americans about the attack on the U.S. Consulate in Benghazi, Libya, may have contributed to Romney’s rise and galvanized his support, but appears to be a less significant factor, according to the poll.

Most voters — 71 percent — said the Libya issue did not affect their choice for president. However, 22 percent of voters — mostly Republicans and enthusiastic Romney supporters — said it made them less likely to vote for Obama.

Romney clearly has an enthusiasm edge right now. Among Maine voters who said they are “extremely enthusiastic” about voting for president this year, Romney leads Obama 46 percent to 35 percent.

Obama’s shrinking lead does not mean Maine will become a new battleground state in the presidential campaign, Brewer said.

“It’s certainly less than the president had a few months ago. That being said, 7 (percentage) points is still a pretty big gap,” he said. “I just can’t see with (two days) left, the Romney campaign is going to come and devote time and resources here.”

The new poll indicates that Romney’s gains in Maine have all been in the more liberal 1st District, however. Obama’s lead has held steady in the 2nd District, the poll shows.

The poll suggests Obama’s statewide lead will hold.

Supporters now appear to be well entrenched, with only 2 percent of each candidate’s backers indicating they could change their minds. Just 6 percent are now undecided, according to the poll.

Perhaps most important for Obama, the president is holding his lead among Maine women, 54 percent to 39 percent, the poll shows. That outweighs Romney’s lead among men, 46 percent to 44 percent.

This is the first poll to indicate that Maine’s gender gap could result in men and women voting for different presidential candidates. In the past two Critical Insights polls, men narrowly supported Obama.

THE BATTLE FOR MARRIAGE

The 13-point lead for Maine’s same-sex marriage referendum is sure to fuel optimism among supporters. Experts say the final outcome will be much closer, however.

The polls show opposition increased from 36 percent in September to 42 percent last week, and the trend is expected to continue through Election Day.

Support and opposition is now virtually even in the 2nd Congressional District — 49 percent to 48 percent. Supporters outnumber opponents in the 1st District, 61 percent to 36 percent.

Advertising by opponents is likely playing some role in the tightening poll numbers. But experts say they have seen this pattern before with votes on same-sex marriage, both in Maine and elsewhere.

Undecided voters and some less committed supporters become “No” voters in the final weeks and days of the campaign. And, a certain number of Maine voters — about 4 percent, experts say — tell pollsters that they support same-sex marriage because it is politically correct, but then vote against it in the privacy of the voting booth.

“There’s a social desirability bias,” Brewer said. “There’s going to be a certain number of people who say one thing to pollsters and vote the other way.” Nevertheless, the marriage proposal has a large buffer of support approaching Election Day. In fact, 52 percent of voters said they are definite about their support, meaning they are least likely to change their minds.

THE RACE FOR SENATE

King, an independent, has seen his lead in the polls bend, but not break.

He led Summers, the Republican, by 28 points in June and 16 points last week, the polls say.

“There was a floor where King wasn’t going to fall under, and a ceiling where Summers wasn’t going to rise over,” Brewer said.

King now has 67 percent support among Democrats but has dropped to 54 percent among independents, some of whom have moved to Summers, according to the poll. Summers leads King among Republicans, 70 percent to 22 percent.

King’s drop over the past few months is attributed to the roughly $4 million in out-of-state money spent on anti-King television ads. He appears to have withstood the attacks with the help of nearly $3 million in outside spending that defended him or attacked Summers.

Two of the major anti-King groups, the U.S. Chamber of Commerce and National Republican Senatorial Committee, stopped spending on the Maine race in October, indicating that internal polls also showed little chance of a Republican victory.

THE RACE FOR U.S. HOUSE

Pingree has seen her lead drop from 31 points in September to 19 points in the latest poll.

Courtney, the state Senate majority leader and Republican nominee, has narrowed the gap by picking up the support of undecideds.

The tightening in the 1st District may partly reflect increased enthusiasm among Republicans spilling over from the presidential race.

Michaud also holds a commanding 19-point lead over Republican state Senate President Raye, according to the poll.

Michaud’s lead has actually appeared to widen since the last Critical Insights poll in September, when he led by 15 points. A relatively large number of 2nd District voters — 10 percent — said they are still undecided.

Staff Writer John Richardson can be contacted at 791-6324 or at: jrichardson@pressherald.com