My advice to Obama, were he to solicit it, would be to simplify this and pick the nominee he thinks would be the most outstanding jurist. Nominate somebody you would love to see on the Supreme Court, an asset to the nation for 30 years if we should be that lucky, and let the chips fall where they may as regards confirmation. Such selection process is rarely quite that simple and clearcut in judicial terms, so if it's down to a list of two or three, maybe weed out the one who is farthest left, if that one really is FAR left. But don't nominate someone mainly on the grounds of confirmability. The scenario you don't want at the end of all this is "we won! we won! ... wait, isn't there some way we could have lost?" And don't bother at all with electoral calculus. Regardless of who is nominated, the political machines on both sides will be adept at milking it for short-term advantage as they perceive it.