To Nudge, Shift or Shove the Supreme Court Left

The potential for President Obama to choose members of the Supreme Court is almost surely to come up within his term in office. I am curious as to the type of person he will try to put in because it will be a good measuring stick as to whether he is truly trying to be bipartisan as he says he is. With the likelihood that those he will have to replace with be Justice Stevens and Ginsburg, the liberal angle on the court will be depleted. He almost will have to put in liberals to replace them, but how strongly they favor liberal viewpoints will be of the most importance.