Republicans Should Employ the Democrat's Judicial Standard
"I've argued many times that Republicans must apply whatever standard the Democrats use when a Republican president makes a Supreme Court nomination. For if the two political parties don't employ the same standard, one of them will have an unearned advantage when it comes to what is arguably our most important institution.
The standard used by Democrats (including President Obama before he was president) is that it's appropriate to vote against a nominee based on nothing more than pure political disagreement. It was on this basis that 40 of 44 Democrats voted against Justice Alito. So that's the standard Republicans should adhere to now. ...
The deference regime crumbled fairly recently when Democrats came to rely so heavily on the Supreme Court to bring about changes they could not enact through the normal political process. With the stakes thus raised, the Democrats felt they needed more of a say even when they didn't control the executive branch.
There is, in fact, a strong argument that, with the Supreme Court as influential as it is now, and with Justices now vetted to the point that they can reasonably be expected to adhere to the philosophy of the president who appoints them, Congress should have a major say in the selection of Justices. Such a say implies the prerogative to vote down nominees based solely on considerations of political ideology."
A good representation of this standard in practice is then Sen. Obama's justification for voting against Justice Roberts and Alito. VDH sums it up:
"[Obama] simply confessed two things: one, the two nominees were qualified; two, their politics made them too unsympathetic to his own political agenda, so they should be rejected."
Although Republicans should be more principled than then Sen. Obama, now President Obama has no reason to object to Republicans voting against Sotomayor based on her politics. They would only be following his standard.