This time, it is through his choice of a Supreme Court Justice to replace David Souter. It's Sonia Sotomayor.
Sotomayor, like Obama himself, is the furthest left non-fringe person in her branch of politics (the law).
Most judges seek a color and gender blind standard of law. Not so Sotomayor who openly does the opposite, with the stated concurrence of her "boss."
In his usual way, Obama did give passing consideration to other, more mainstream, candidates like Governor Jennifer Granholm. But in the end, he went where his heart was.
And Supreme Court candidates are rarely defeated in Congress, unless there is a "smoking gun," so Sotomayer is a heavy odds-on favorite to be the next Supreme Court Justice.