From NBC's Mark Murray
The AP is reporting -- and First Read has confirmed -- that Wyoming Gov.

Dave Freudenthal, a Dem superdelegate, is endorsing Obama.

That brings our superdelegate count to Clinton 255, Obama 222.

Overall, with pledged delegates added, it's now Obama 1,638, Clinton 1,507.

*** UPDATE *** Since March 4, Obama has picked up 11 superdelegates to Clinton's one.