The Interest Groups

November's election isn't likely to turn on Human Rights Campaign's endorsement of Sen. Collins. But since the junior senator's success with voters depends on convincing them she's a moderate, there are some other progressive organizations whose verdicts will matter: If she's embraced by moderate, left-leaning groups, this will inevitably solidify the impression among voters that Collins is who she says she is.

Conversely, if Collins finds herself attacked by progressive organizations, independents and Democrats who've supported the junior senator in the past will surely take note of that as well.

So it will be interesting to see how these endorsements shake out, whether any organizations decide to sit on the sidelines, and whether those who do take sides back their words up with fundraising, organizational support, etc.