The Democrats pushed campaign finance reform. One of the pieces of reform involved coordination. Groups and candidates couldn’t coordinate their attacks and strategies. According to the New York Times, the Democrat groups are really pushing the line:
[T]he fund-raising groups helping Mr. Kerry say they plan to continue their campaigns until an election commission ruling says otherwise. Already, the groups have brought together some of the best organizers in their fields. And some are literally under the same roof in a building just blocks from the White House.