AUGUSTA — Former Gov. Angus King has a big lead early in Maine’s race for a U.S. Senate seat, and President Barack Obama has an edge among Maine voters over likely Republican nominee Mitt Romney, says a poll released Friday by the Maine People’s Resource Center.

The center is affiliated with the Maine People’s Alliance, a liberal advocacy group. The center was the first to release poll results last year showing Portland mayoral candidate Michael Brennan leading his 14 rivals. The findings drew criticism of the center’s polling methods, but Brennan ultimately won and the poll proved accurate in ranking the top nine candidates.

Because it is so early in the Senate campaign, the center’s communications director said Friday that the new poll results must be kept in perspective.

“What these numbers mostly show is name recognition,” said Mike Tipping in a written release. “These results tell us where candidates are starting, not where they’ll end up.”

The June 12 primary elections for U.S. Senate appear to be up for grabs, with the biggest blocs of Democrats and Republicans undecided, according to the survey of nearly 1,000 likely Maine voters.

Among voters who support a candidate, state Sen. Cynthia Dill, D-Cape Elizabeth, and former Secretary of State Matt Dunlap are in a statistical tie for the lead in the Democratic race. Secretary of State Charlie Summers leads all other candidates in the Republican contest, with more than twice the support of the second-place candidate, state Treasurer Bruce Poliquin.

In a prospective general election matchup of Summers, Dunlap and King, the independent former governor leads with 56 percent of the vote, and the Republican and Democratic candidates trail by wide margins. King has larger shares of unenrolled and Democratic voters than he does Republicans.

The poll suggests that Obama leads Romney, with 54.6 percent of the vote, in a head-to-head race in November. That is consistent with national groups that rate Maine as leaning Democratic in the presidential race.

The Maine poll indicates that the hypothetical presidential race is closer in the state’s 2nd Congressional District, also as expected.

In Maine’s two U.S. House races, the poll shows incumbent Democrats Chellie Pingree in the 1st District and Mike Michaud in the 2nd District with strong leads over Jon Courtney and Kevin Raye, respectively.

Courtney and Raye face primary challengers in June but are considered the likely nominees.

A majority of respondents — 58 percent — said they support legalizing same-sex marriage in Maine. That support is similar to, though slightly higher than, support found in a poll last month by Public Policy Polling.

The Maine People’s Resource Center says it surveyed 993 registered and likely voters from March 31 to April 2. The margin of error is 3.11 percentage point at a 95 percent confidence level, the group says.

The poll was done with automated phone calls. Some traditional pollsters who use personal interviews say the automated method is inconsistent, with results that are wrong as often as they are right.

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