Last I checked, presidents are elected for four years, not three. Which means President Obama should quickly nominate a replacement for Justice Antonin Scalia. Then the Senate should play its assigned role.
For the Senate to shut down the confirmation process would be bad for the court, bad for the country and, ultimately, bad for Republicans.
It would be bad for the court because it would leave a vacancy for more than a year, stretching across two terms and, in any number of important cases, preventing a majority from having a definitive say. (A four-four split affirms the lower court ruling and lacks value as precedent.)
It would be bad for the country for similar reasons. Citizens deserve conclusive answers on issues important enough to reach the high court, and divisive enough to split the justices, whether that involves Obama's executive actions on immigration, Texas' restrictive abortion law or the role of public-sector unions. They also deserve a functioning political process. Refusing to go forward would serve to deepen and entrench the existing partisanship and ensuing gridlock.