Chuck Hagel Received Funding from "Friends of Hamas"?

I wonder if this is true or is just an attempt to force him to disclose who he has received funding from these last few years (he has refused so far).  From Breitbart:

On Thursday, Senate sources told Breitbart News exclusively that they have been informed that one of the reasons that President Barack Obama's nominee for Secretary of Defense, Chuck Hagel, has not turned over requested documents on his sources of foreign funding is that one of the names listed is a group purportedly called "Friends of Hamas."

...

Called for comment and reached via telephone, Associate Communications Director at the White House Eric Schultz identified himself, heard the question, was silent for several seconds, and then hung up the phone immediately without comment. Called back via the White House switchboard, Schultz's phone rang through to his answering machine. Called on his cell phone, Schultz's phone rang through to his answering machine.