A new poll shows independent Angus King is a heavy favorite to replace U.S. Sen. Olympia Snowe as well as strong support for a referendum question that would allow same-sex couples to legally marry.

The poll was commissioned by WBUR, the Boston affiliate of National Public Radio, and conducted by the independent think tank MassINC Polling Group. The survey of 506 likely Maine voters took place between June 13-14 and has a margin of error of 4.4 percentage points.

The survey asked respondents who they would vote for to replace Snowe. The results show 50 percent picked King. Republican Charlie Summers drew 23 percent while Democratic state Sen. Cynthia Dill had 9 percent.

King, who served two terms as governor, is also the best known candidate in the field and enjoys a 60 percent favorability rating. Summers by contrast has a 27 percent favorability rating with 31 percent of respondents saying they have heard of him but have not yet made up their mind about him.

Fourteen percent of respondents had a favorable view of Dill, but a plurality of respondents, 35 percent, said they had never heard of her.

The survey also showed President Barack Obama ahead of Republican challenger Mitt Romney, 48 percent to 34 percent. The president’s margin increased to 26 percent among female voters and he leads 50-24 among independents. Male voters were split between Obama and Romney.

Gov. Paul LePage remains a polarizing figure, according to the survey. Forty-nine percent of respondents have an unfavorable view of his job performance while 40 percent approve. LePage has a 64 percent approval rating among Republicans, but his favorability is lower among Democrats (21 percent) and independents (36 percent).

Respondents split on whether Maine was headed in the right direction with 39 percent saying ‘yes’ and 39 percent saying ‘no.’ Another 22 percent either didn’t know or refused to answer.