"there’s been disturbing reports recently that he’s got a ... secretive Bermuda corporation that no one knows anything about".
Well, there you have it; "disturbing reports", rumors. And where do these disturbing reports come from? Some liberal hack in the media, or did Wasserman Schultz just make it up?
This is typical liberal playbook tactics: it's not the lack of evidence, but the seriousness of the accusation that demands an investigation.
And even if Romney has offshore bank accounts, SO WHAT! Why is that important? What does that have to do with anything?