Senator Susan Collins’ lead in her bid for reelection in Maine continues to fade, according to the latest Rasmussen Reports telephone survey.

Two months ago Collins led her Democratic challenger Tom Allen by 16 percentage points, but that spread fell to 10 points in May. Now her lead is down to seven points, 49% to 42%, dropping her below 50% for the first time and putting her among the Republican senators at risk this November. Incumbents who poll less than 50% are generally viewed as potentially vulnerable.

Collins’ favorability rating has fallen as well for the third month in a row, but she is still is viewed favorably by a substantial majority of Maine voters (65%), down from 70% last month. By a nearly identical number, the incumbent’s unfavorables have risen from 29% in May to 33% now.

By contrast, Allen, who has served in the House since 1997, is viewed favorably by 56% of voters and unfavorably by 37%, virtually identical to his ratings in May.

Collins, who is seeking a third term in the Senate, leads Allen by 14% among men but has just a two-point edge among women voters.

She also has lost support from voters in her own party – with 81% of Republicans now backing Collins compared to 89% a month ago. Allen now earns support from 12% of the state’s Republican voters, up from 9% last month.

Among Democrats, Allen’s support has increased to 72% this month, up from 64% in May. Twenty-four percent (24%) still support Collins.

However, when it comes to unaffiliated voters, Collins leads 52% to 34%. These numbers represent a major improvement for the incumbent since last month when the two candidates were tied at 44%.

Collins is far from being the only Republican incumbent at risk in the 2008 Senate elections. At least nine other Republican Senate seats are potentially in play for Democrats including seats in Kansas, Alaska, New Hampshire, Oregon, New Mexico, Colorado, Mississippi, Virginia, and Kentucky. So far, just two Democratic incumbents are polling below 50%--Mary Landrieu in Louisiana and Frank Lautenberg in New Jersey.

In Maine, Democrat Barack Obama holds a wide lead over John McCain in the Presidential race.

Rasmussen Markets data gives Collins a 71.0 % chance of keeping her job this November. Numbers in this paragraph are from a prediction market, not a poll. We invite you to participate in the Rasmussen Markets. It costs nothing to join and add your voice to the collective wisdom of the market.

Maine Governor John Baldacci, a Democrat, earns slightly better marks in the new survey, with 33% of voters rating his performance good or excellent, up from 28% last month. Thirty-two percent (32%) of voters say he is doing a poor job as governor, down from 35% in May.

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