Looks like Senator Chuck Schumer (D-NY) is asking the same questions we've been asking. Namely, what's the relationship between the Renzi corruption investigation and the firing of US Attorney Paul Charlton? In a letter to Attorney General Alberto Gonzales, Senator Schumer asked for a full accounting of all contacts between Rep. Renzi, the White House, and the Justice Department related to the corruption investigation. According to Schumer, it's more than just the firing of Charlton, it's about obstruction of justice. From the Hill article:
In addition, Schumer is concerned about a report in the Wall Street Journal that the Justice Department failed to approve Charlton's key requests, in effect preventing the U.S. attorney from moving forward in the Renzi corruption probe until after the election. One month later, Charlton was asked to resign his post.
No public response from Gonzales or the White House yet.