This is genuine "culture of corruption" material, a much bigger deal than the Jefferson indictment.
The deal is that almost all Senators are okay with requiring that their campaign finance information be filed electronically. However, he's stopped the effort to do so, and is covering up the other senator involved with this:
As Senate Minority Leader, he is also hiding the identity of an anonymous Republican senator whose objections to “The Senate Campaign Disparity Act” (S. 223) have stymied efforts to give the public more information on sources of campaign contributions in the Senate.
The irony in this situation is that there is a secret objection to legislation that would generate more transparency for senators.
For more, check out What's McConnell Hiding?