Insofar as opposition is starting to crop up to the Eric Holder AG nomination, it's being centered around Holder's role in the controversial Marc Rich pardon in the waning days of the Clinton administration. The fact that Holder is liberal, by itself, is not disqualifying -- Barack Obama, rumor has it, is liberal (if not "THE MOST MARXIST/FASCIST SENATOR EVER!"). The National Review brings up the pardon in its editorial opposition to Holder, citing a Congressional report labeling his participation "unconscionable". What they don't tell you, but McCain supporter Orin Kerr does, is that the report was released by Rep. Dan Burton (R-IN), a rabid Clinton hater famous for not just insisting that Vince Foster was murdered, but actually "re-enacting" the event by shooting a pumpkin in his backyard.
I, too, came across Rep. Burton when I attended Congressional hearings regarding formaldehyde contamination in FEMA trailers. To pass the time, I gave grades to the various committee members. Burton came in dead last, with a D+, since his entire contribution was assuring the rest of the committee that he knew the CEO's of the corporations in questions and was confident they would never hurt a fly. If only Mr. Holder knew that all this nastiness could have been staved off with a cocktail party, we might all be better off.
You can take a look at Rep. Burton's wikipedia page, if you'd like. He's got all manner of crazy in his closet.