While there is a tendency to replace like with like, that's because Supreme Court justices usually time their retirements to coincide with presidencies that share their views.
In this case, I doubt it applies. In theory Obama could pick a nominee closer to the center to avoid a tiresome confirmation battle, but I suspect there's a bigger bang for the buck in nominating fairly left-wing candidates and making the Republican Senate choose between looking obstructionist to the general public or looking weak to their base.
Could you explain why this might cost the Republicans votes? Their core voters would absolutely love them standing up to the "tyranny" of Obama. Even independent/undecided voters would understand that its reasonable enough to postpone considering how close the Presidential election is.
To be clear, I think it would be best to have it completed within 3 months, like the previous 10 nominations to the court but I don't think it will cost the Republicans at all to postpone it till next year.
You might very well be right, and I agree that the Republican base would prefer that the Senate just doesn't bother to consider a nominee until after the election.
However, my impression is that independent voters prefer action to inaction and typical behavior to atypical, and will be susceptible to 'the Senate is refusing to do its job' arguments from the President and the Democratic presidential nominee, as well as 'Supreme Court appointments are usually approved in XX days' arguments from the press.
It can be a good call to arms for the Democrats though. If the nomination is withheld long enough, lobbies like EMILY's list will get more donations and will raise more noise. and rightly so because more is at stake.
In this case, I doubt it applies. In theory Obama could pick a nominee closer to the center to avoid a tiresome confirmation battle, but I suspect there's a bigger bang for the buck in nominating fairly left-wing candidates and making the Republican Senate choose between looking obstructionist to the general public or looking weak to their base.