The Republican-controlled U.S. Senate should not for political expediency shirk its constitutional responsibility. President Obama said he will nominate a candidate to replace the late Justice Antonin Scalia. The Constitution makes clear it is then the job of the Senate to provide its “Advice and Consent” by either affirming the nomination or rejecting it.

Instead, in highly politicized comments delivered just hours after the passing of Justice Scalia, Republican Senate Majority Leader Mitch McConnell of Kentucky declared, “This vacancy should not be filled until we have a new president.”

Refusing to act on an Obama nomination would disenfranchise the 65,915,796 Americans who voted to re-elect the president and renew his power of appointment. If this vacancy occurred late in the president’s term, next August or September, perhaps McConnell’s position might have some validity. However, there is nearly a year left in the Obama presidency.

At what point, Mr. McConnell, does a president no longer deserve to have his nominations acted on? If a vacancy occurs halfway into a president’s second four-year term should the country have to wait two years to have a fully functioning court? Or perhaps as soon as Obama won re-election his power to appoint to the Supreme Court effectively ended.

Does that sound absurd? Well, so does McConnell’s position, a position unfortunately mirrored by Republican candidates running for president.

The nation needs a functioning Supreme Court. Take the case addressing the Affordable Care Act’s birth control mandate. Nonprofit and religious institutions are challenging the constitutionality of the requirement that employers provide their female employees with health insurance that includes no-cost access to certain forms of birth control. Some lower appellate courts upheld the requirement, while others ruled it unconstitutional. A 4-4 tie on the Supreme Court would leave the conflicting decisions standing, an outcome inviting legal confusion and chaos.

Given the political realities, President Obama should nominate a judicial moderate who received substantial Senate support from Republicans in his or her prior appointment to a federal bench seat. If Obama fails to do this, and Republicans conclude he is offering a justice far outside the judicial mainstream, they can withhold consent − but they should act.

In February 1988 — the last year of Republican President Reagan’s second term — the Senate unanimously approved the appointment of Justice Anthony Kennedy after the Democrats blocked Reagan’s first choice, ideologue Robert Bork.

That is how the system used to work and should again.