Barack Obama is on an impressive run -- since Super Tuesday, he has picked up the public endorsement of 64 superdelegates, while Hillary Clinton has tallied only nine. Even after that string of victories, though, Obama remains behind Clinton in most superdelegate counts (these counts tend to vary from media outlet to media outlet, but it's certainly the common wisdom that Clinton is ahead in superdelegates, at least for now), but he's gaining fast.

The Wall Street Journal reported Monday that North Carolina's seven Democratic members of Congress -- all of whom are superdelegates -- will endorse Obama sometime before their state votes on May 6. Also Monday, Obama received the endorsement of Minnesota Sen. Amy Klobuchar.

Moves such as these are being widely interpreted as a sign that superdelegates are impatient with the continuing race, and worried about the impact it will have on November voting. The WSJ ties Klobuchar's endorsement to Pennsylvania Sen. Bob Casey's own recent endorsement of Obama and notes, "Both senators had planned to remain neutral, according to party officials, but decided to weigh in as the Democrats' campaign became more negative and Sen. McCain was free to exploit the confusion looking to the November election."

Update: Salon's Mike Madden is covering Obama today; he reports that an Obama spokeswoman has told him that they aren't getting as many endorsements as the WSJ says. "We don't share the Wall Street Journal's optimism," the spokeswoman said.