Take a glance at any of the dozens of rankings and rundowns of the most vulnerable senators up for reelection this year and you'll find that Susan Collins (R-Maine) is nowhere to be found.
The past few days are a clear illustration of why.
Collins has rounded up the support of key environmental and gay rights groups designed to serve as a firewall against her liberal Democratic challenger —who arguably could also lay claim to the same endorsements, if not for Collins's position of power.
On Monday, Collins won the support of the League of Conservation Voters, an environmental group that mostly backs Democrats and is known for spending sizable sums of money in congressional races. For example, the group, which also endorsed Collins in 2008, just dished out $457,000 on a TV ad buy in the Iowa Senate race.
Last week, she won the backing of the Human Rights Campaign, a leading gay rights group. Just hours later, Collins became the fourth Republican senator to come out in support of gay marriage.
The endorsements Collins just won amount to a lesson about the power of incumbency. She is very popular back home and considered a safe bet to win reelection. By offering her their support, groups from the left such as LCV and HRC can bolster the odds that she will support their causes in the future. By opposing Collins and supporting a long-shot incumbent against her, they would do themselves no favors in the long run, assuming she wins another term.
Collins's Democratic opponent is Shenna Bellows, a former executive director of the American Civil Liberties Union running on a staunchly liberal platform. Bellows is no pushover — she has the endorsement of the Democratic Senatorial Campaign Committee, she's raised money at an impressive clip, and she has caught the attention of left-leaning national groups.
And yet, few observers give her a real shot of seriously competing against Collins, because of the senator's popularity.
In a statement, Bellows's campaign pointed out that Collins's lifetime score of 67 from LCV is not all that impressive. LCV noted that it was the best of any Senate Republican.
"I've been a consistent voice for more renewable energy, stronger clean air and water standards and an end to the Keystone XL Pipeline project, and I'll proudly stack my environmental values against Mitch McConnell, Susan Collins and any other Washington Republican," Bellows said.
At a time when political polarization runs rampant and primaries have increasingly become sprints to the left or right, Collins is a rare breed: a moderate capable of winning the support of Democrats and Republican voters and groups.
It all works because Maine is a state with a tradition of political independence where being staunchly conservative is not the way to go for Republicans. Consider:
— The state's other senator is Angus King, an independent former governor who caucuses with the Democrats. He succeeded Republican Olympia Snowe, a moderate like Collins.
— Gov. Paul LePage (R), seen as more conservative than much of the state, is in serious danger of being unseated this year.
— President Obama won Maine by 15 points in 2012.
All of which explains the centrist profile that Collins has carved out — and why it's worked so well. (Collins won her last two reelection campaigns by double digits.)
The general election threat — albeit a minor one at this point — presented by Bellows may have forced Collins to stake out a harder position on gay marriage now and roll out the LCV endorsement sooner than she otherwise would. But she was always going to emphasize her crossover appeal sooner or later.
Nationally, moderation may be in short supply in politics. But there's plenty in the Maine Senate race. And Collins knows just the line to walk.