According to the New York Times the nurses SuperPAC has outspent all others in the Democratic race so far.
But the union is not just busing nurses into Iowa. The union’s “super PAC” has spent close to $1 million on ads and other support for Mr. Sanders, the Democratic presidential candidate who has inspired liberal voters with his calls to eradicate such outside groups. In fact, more super PAC money has been spent so far in express support of Mr. Sanders than for either of his Democratic rivals, including Hillary Clinton, according to Federal Election Commission records.
Hillary’s SuperPAC has been holding its fire for the general, against the Republicans rather than a fellow Democrat.