In choosing a Supreme Court nominee to replace Justice Souter, President Obama will have an opportunity to avoid the partisanship he promised to reduce on the campaign trail, which his legislative agenda has thus far only exacerbated.

But given the way Bush nominees were treated by Senate Democrats, it won’t be easy. After the stormy confirmation hearings for Judges Bork and Thomas, President Clinton’s nominations of Judges Ginsburg and Breyer sailed through the confirmation process with little opposition and even less acrimony. With the return of Republican nominees after the election of George W. Bush, however, Senate Democrats resumed their scorched earth practices, starting with appellate court nominees and continuing to the nominations of Judges Roberts and Alito to the High Court.

Hearings were never held, filibusters were threatened and reputations were tarnished.

The question now for Senate Republicans will be, is turnabout fair-play?

The answer may turn on just who President Obama selects. At the least, given this recent history, there is no reason Senate Republicans need to be unduly deferential to the president’s nominee. We will need to know both the judicial philosophy and the constitutional philosophy of the nominee.

That will require respectful but sharp questioning by members of the loyal opposition. Their duty under the Constitution requires nothing less.