Senator John McCain just got caught in a "Kinsley gaffe," which is defined as: "a Washington politician accidentally admitting an obvious truth." For which I'd like to thank McCain, because it could actually pave the way for Senate Democrats to combat Republican obstructionism in a very effective manner. McCain's gaffe was on the subject of the Senate's confirmation process for Supreme Court justices. He confirmed what some had already been suspecting -- if Hillary Clinton becomes president, the Senate Republicans might just band together to refuse to confirm anyone she names to the high court. Period.

Here are McCain's own words, from a Pennsylvania interview where McCain is trying to boost Pat Toomey's chances of being re-elected:

I promise you that we will be united against any Supreme Court nominee that Hillary Clinton, if she were president, would put up. I promise you. This is where we need the majority, and Patrick J. Toomey is probably as articulate and effective on the floor of the Senate as anyone I have encountered.

Pretty straightforward. McCain later tried to walk this comment back, but the cat's really out of the bag at this point. Republicans -- whether they continue to hold the Senate or not -- will not be voting on any Democratic Supreme Court nominee until a Republican occupies the White House. This deliberate obstructionism was pretty easy to predict, but no senator has actually admitted it, until now.

If the Republicans continue to control the Senate after the election (which is a very real possibility -- Hillary Clinton's coattails may be quite short), then they're free to block all Supreme Court nominees for as long as they think it is a politically advantageous thing to do. So far, they haven't paid much of a political price for obstructing President Obama's latest Supreme Court pick, so perhaps the public won't mind them continuing to do so next year. If this turns out to be the case, there is nothing Democrats can do about it but try to make it a political liability for Republicans. They'd have to effectively take their message to the people to do so, however, because they'd be otherwise powerless in forcing Mitch McConnell to act.

Even if Democrats regain control of the Senate, nobody in their right mind is predicting they'll gain a 60-vote supermajority, which is what would be required to avoid all Republican filibusters. So even if Chuck Schumer is our next Senate Majority Leader, Republicans could still stymie President Hillary Clinton's Supreme Court picks.

Unless Schumer goes nuclear, that is. The former Democratic leader of the Senate, Harry Reid, already used the first "nuclear option" in the arsenal. He did so by changing the Senate filibuster rules. Before Reid did so, Republicans could filibuster every judge and other presidential appointee, to their hearts' content. When Reid finally got fed up with the rampant obstructionism on judicial appointees, he changed the rules (with a majority vote) to bar the use of the filibuster from all judicial appointees altogether. This led to a lot of Obama's nominees quickly getting confirmed, ending their months-long wait.

But in doing so, Reid avoiding nuking the filibuster for both Supreme Court justices and for legislation. Interestingly, even though Republicans have retaken the chamber since Reid dropped his nuke, they have not bothered to change the rules back. They didn't really need to (when you're in the majority, you don't need filibusters to work your will), but it's still interesting that they left Reid's change intact.

But if Democrats retake the Senate, there is a very easy process to nuke the Supreme Court confirmation filibuster, as well. After every 2-year election cycle, a new Congress is seated. The first thing both houses do is to vote on their rules for the next session. This is done by majority vote. So if Schumer wanted to, he could remove the Supreme Court filibuster from the rules at the very start.

Politically, this might previously have been seen as somewhat risky. The Republicans are going to howl if it happens, but all Democrats would have had to do would have been to point to the refusal of the Senate to vote (or even hold hearings) on Merrick Garland, Obama's current nominee. Such obstructionism is unprecedented in modern times, so Democrats would be on firm political ground.

But now John McCain has made nuking the Supreme Court confirmation filibuster immeasurably easier. Because now all Schumer has to do is quote McCain on the issue. "Republicans are already saying they're going to block any nomination from President Clinton, so we have to act or else we're going to have a vacancy on the court for the next four years, at least," is all Schumer has to say now.

Schumer should really drop this nuke, even if Republicans were to wise up and confirm Garland during the lame-duck session. They'd be smart to do so for two reasons: Garland is nowhere near as liberal as many other choices Clinton could make, and Garland is older than anyone Clinton is likely to nominate. So they'd get a fairly moderate justice who wouldn't be on the court for all that long (when seen historically). But even if Garland is confirmed by Christmas, Schumer should still act.

In the first place, it's a lot easier to change the rules at the very beginning of the session. In the second place, Clinton will likely get at least one (perhaps even two or three) appointments to the Supreme Court during her term in office. So the problem's not going to go away even if there is no vacancy on the court when she is sworn into office.

So the smart thing to do would be to drop the second nuke next January. This would result in a Democratic Senate being able to confirm anyone Hillary Clinton names to the high court, by majority vote alone. No filibusters (and no naked political obstructionism) would be possible. As, indeed, the Founding Fathers intended (the filibuster is not in the Constitution at all).

For making it about a hundred times easier for Chuck Schumer to get rid of the Supreme Court filibuster, I would like to personally thank John McCain. As all Democrats should. Thanks, John, for making it so easy for Schumer to act!

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant