Coakley's campaign warned the DNC about the problems her races was having all along, Coakley's campaign thought that race was about health care bill

From the Politico:

Coakley's lead dropped significantly after the Senate passed health care reform shortly before Christmas and after the Christmas Eve "bombing" incident. Polling showed significant concerns with the actions of Senator Nelson to hold out for a better deal. Senator Nelson's actions specifically hurt Coakley who was forced to backtrack on her opposition to the abortion restriction amendment.

Of course, the national Dems say that this is just a local race: "Local issues at play" and that the other side simply ran "a very clever campaign." Nothing special going on in this race that has implications for Washington politics. I don't believe that many reporters will believe this spin.