If he goes, the bargaining then becomes, if Rosenstein gets an acceptably severe punishment, will you Republicans stop it there? They want to make sure it stops well before Obama. That is the trigger.
Unfortunately for the Dems, they were/are incredibly in-your-face corrupt. They weren't trying to hide their corruption, they were BRAZEN with their corruption. IRS scandal, Email scandal, Wire Tapping scandal, Fake evidence to support Fisa court scandal. Over and over again, they were BOLD with their corruption. Clinton Lynch tarmac scandal, Writing exoneration memo before Clinton interview scandal, allowed Clinton to be interviewed - probably gave her the questions ahead of time - scandal, Clinton SMASHES subpoenaed hard drive equipment scandal. They send out press releases regarding their scandals. They literally thought they were invincible and above the law.
Trump is a closer. The Art of the Deal.