Can the Supreme Court do its job this year with just eight justices? As the court's vacancy enters its second month, Republicans now appear to be saying: Sure. Why not.

The "sky won't fall" with just eight on the court. That is the headline in a Des Moines Register op-ed by Sen. Chuck Grassley (R-Iowa) published Sunday. Grassley was responding to a Des Moines Register editorial calling Republicans' blockade "un-American" and specifically singling out Grassley, chairman of the Senate Judiciary Committee, for blame.

"It's entirely American," Grassley argued.

So, who's right? Or really, who's argument has the most political leverage?

For that, we'd have to go with Grassley. His main point is that the court has sat with six, seven and even up to 10 justices at different points in history — and still managed to function. "The size of the court as Congress designed it over the years has frequently changed," he writes, "and hasn’t left the court in disarray."

That is true. There's no constitutional mandate that there has to be nine justices. It's the same reason Republicans feel they can block President Obama's nominee for the rest of 2016: There's no rule saying they have to approve or even consider Judge Merrick Garland, the nominee.

History, of course, can be cherry-picked. The periods that Grassley is citing — when the Supreme Court had more or less than nine justices — were products of extenuating circumstances, and that is not the way the court was designed to function. Section 28 Title 1 of the U.S. Code says there "shall" be nine: "The Supreme Court of the United States shall consist of a Chief Justice of the United States and eight associate justices, any six of whom shall constitute a quorum."

But if the Supreme Court is based on precedent, this confirmation battle is rooted in politics. Both sides are holding their ground with an eye on how doing so will play out for them in November, and Republicans think holding off on filling that vacancy could be a winning issue for them.

Which is why Grassley can get away with the case he is making now. This Supreme Court confirmation battle is about rallying the base, and there's no reason conservatives and conservative judicial activists wouldn't pick this "Why not eight?" case and run with it. It could fit nicely with their rallying cry, "Let the people decide," which could become: "Letting the people decide next year is more important than a few split decisions this year."

Republicans also are betting that an open spot on the court won't send independents to the polls in droves to vote against them. (And polling suggests they're right.) So why not take that a step further and explain to voters why eight justices isn't that big of a deal?

This Supreme Court confirmation battle is also rooted in outcomes in the court. Split decisions are the most likely outcome of some of the most controversial cases before the court this election year, and they aren't always a bad thing for Republicans. A 4-to-4 decision by the Supreme Court is basically a non-decision, so it affirms the lower-court ruling. The Supreme Court has split twice since Antonin Scalia's death; one deadlock on unions favored Democrats, the other on contraceptive coverage under the Affordable Care Act is TBD.

There's an even bigger case coming up in which a split decision would be great for Republicans. If the Supreme Court falls 4-to-4 on whether Obama's executive action on immigration is legal, it would stop the program from going forward. That means about 4 million undocumented immigrants would no longer be protected from deportation relief, and Republicans would celebrate a huge legal and political victory — if only, perhaps, a temporary one — right before the election.

Such a scenario most certainly wouldn't have been a possibility if Republicans had moved quickly to confirm Garland.

Republicans may just be bringing up the "Sure, why not eight justices?" argument because their opponents are trying to make the size of the court an issue. (Grassley was responding to that Des Moines editorial, after all.) But if they wanted to run with this, it probably wouldn't hurt them — because talking about a deadlocked court probably won't change a deadlocked debate all that much.

This post has been updated to clarify what the law says about whether there should be nine justices on the court. The law says there "shall" be nine justices, but there is no constitutional mandate dictating that.