I don't think Change to Win's endorsement of Obama will matter much organizationally. By this point, Obama is so well-funded, and his ground games are so deeply planned, that CTW can only offer an assist on the margins. Moreover, the coalition doesn't really have a broad political organization of their own, and have instead been folding their efforts in with the AFL-CIO's -- and the AFL-CIO hasn't endorsed. Much more important will be their impact among superdelegates. The more that powerful Democratic Party interest groups united behind Obama, the less likely it is that superdelegates will heed the pleas of the Clintons. A lot of superdelegates are Congressmen from districts with strong union presences, and they'll take not only Andy Stern's call, but the call from representatives of unions in their district. No matter how this election shapes out, these Congressmen will still need Labor's help. So insofar as a lot of superdelegates seem to want to go with Obama but have a sort of status quo bias that leaves them slightly afraid of crossing Clinton, the calls from established and constant allies who they also don't want to cross could be important.
