A primary challenge for President Obama? (VIDEO)

The topic du jour among liberals in the wake of President Obama's compromise with Republicans on tax cuts is fielding a serious primary challenger in 2012.

The problem? You can beat someone with no one. And, with people like former Gov. Howard Dean and Wisconsin Sen. Russ Feingold already taking themselves out of the running, liberals have no serious candidate around which to rally.

We explain it all in today's "Fast Fix". Don't forget to check out all of our "Fast Fix" daily videos here. And, if you have a topic you want to see us break down in "Fast Fix" just email chris.cillizza@wpost.com with it.