Political calculus

... alternative title for this post:
"Unless things change, they are likely to remain the same."

Conservatives Quickly Refuse Any Obama Court Replacement After Antonin Scalia's Death
"Senate must simply refuse to appoint anybody."

I would suggest to Majority Leader McConnell that this is a very stupid, short-term strategy.

Does he really believe that Trump or Cruz - the two GOP front-runners - will win the general election in November?

Let's imagine for the moment that his political instincts, which have so far served him well, recognize the likelihood of a Dem victory in November...
... a Dem victory accompanied by loss of GOP control of the Senate.

Does he believe either Clinton or Sanders would nominate a less radical/left-wing/progressive replacement for Scalia than would Obama?
Obama recognizes that the GOP now controls the Senate, and is therefore constrained to nominate at least a MODERATE liberal!

Neither Clinton nor Sanders would be so constrained!