Rasmussen Reports issued it's latest poll on the Maine Senate Race:

Maine Senate: Collins Doubles Lead over Allen

Maine Senator Susan Collins has more than doubled her lead over Democratic challenger Tom Allen in the latest Rasmussen Reports telephone survey of voters in the state. The Republican incumbent is ahead 53% to 38%.

When “leaners” are included, Collins leads 55% to 40%.

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The incumbent is viewed favorably by 67% and unfavorably by 29%. Allen’s ratings are 54% favorable, 37% unfavorable.

Collins now enjoys a dominant 55% to 32% lead among unaffiliated voters in Maine. She even earns support from 29% of Democrats. The incumbent leads by identical 53% to 38% margins among both men and women in the state.

RedState had this to say earlier about Rasmussen:

Rasmussen has been notoriously Democrat-leaning this cycle, and explained on their blog a few months back that they are over-sampling Dems by roughly 9%.
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Collins has led in every poll since this race began. Last month, Maine-based Democratic pollster Patrick Murphy showed Collins with a 26 point lead over Allen. Rasmussen is the only poll that has shown Allen within 10 points, reinforcing the contention that they are oversampling Democrats in Maine.