The passing of Justice Antonin Scalia has left a vacancy in the Supreme Court. The Republicans want his replacement to be delayed until after the presidential elections, betting that a Republican will be elected and will assign a conservative judge to take his place. They argue it is inappropriate for a lame duck president to assign a supreme court justice. They conveniently forget that Scalia was appointed by Reagan in 1986 and Justice Kennedy in 1988, both in Reagan's second term.
In its history, the SCOTUS has become increasingly political and strayed far from its original Constitutional purpose. Article III, Section I states "The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish." The operative word in that phrase is "judicial."
It has become the practice of the SCOTUS to not just determine the Constitutionality of a law but to give judgments that become de facto law upon their pronouncement. In essence, Supreme Court Justices have become legislators appointed according to their political leanings and given lifetime assignment to support that particular agenda with the power to make law and enforce that judgment whenever challenged with its own irresistible power.
That is why replacing Scalia before Obama's exit from office is critical to the progressive agenda. He was a conservative, often the deciding vote turning judgments against progressive interests.
With the expanded power of presidential executive action and a progressive SCOTUS, Congress can be bypassed. It becomes irrelevant as far as legislation is concerned. The checks and balances designed by the Constitution are coming under more attack today than ever before.
Many argue that Obama's executive actions are no different from previous presidents', that the number of his executive actions have been fewer and therefore they couldn't possibly have had as much of an effect. They refuse to understand that it's not the number of executive actions but the subjects which they address.
Many argue that SCOTUS rulings don't make law, they interpret the law. However, interpretation of the law is legislation in itself. This power of interpretation was not original to the Constitution. It derives from Marbury v. Madison (1803). It was appropriate that the judgment spun on issues around the president himself. However, over the next decades, that power of interpretation began to be applied to more and more issues, issues that extended beyond the letter of the Constitution and into social and economic private issues.
SCOTUS began to see itself as the conscience of America. And whichever party controls America's conscience controls America. That's why replacing Scalia is so critical to both parties. That single seat is the pivot point for all power in the US government. Not the president, not the Senate, not the House.