Update: Here's Feingold's statement. 

Today Russ Feingold and Dianne Feinstein brought S.223, the Senate electronic disclosure bill, to the floor for a unanimous consent vote. When they asked if there was any objection Sen. Lamar Alexander, filling in for the minority leadership, announced that he had an objection, indicating that some Senator in the Republican caucus has placed a secret hold on the disclosure bill. This is twice in two years that a Senator has placed a secret hold on legislation providing for more disclosure to the public. Last year, it was the Coburn-Obama earmark database bill and a coalition of Right and Left bloggers smoked out both Sens. Ted Stevens and Robert Byrd as the secret holders. Don't these Senators know that we will find out who you are.