The ACU isn't what it seems. Here's a list of the highest rated in the Senate for 2012:
The winners of the “ACU Conservative” award – given to those members who scored 80 percent or higher – in the Senate are: John Barrasso, Richard Burr, Dan Coats, Thomas Coburn, Bob Corker, John Cornyn, Mike Crapo, Saxby Chambliss, Jim DeMint, Mike Enzi, Lindsey Graham, Orrin Hatch, Jim Inhofe, John Isakson, Mike Johanns, John McCain, Jim Risch, Jeff Sessions and David Vitter.