There's a reason the Senate majority rarely goes through with filibuster reform: The minority can make the aftermath hellish.

Will Harry Reid actually change the rules? (Michael Reynolds/EPA)

Robert Dove, who served as Senate parliamentarian from 1981 to 1987 and then from 1995 to 2002, recalls the aftermath of the 1975 filibuster reforms. "My reaction was I don’t ever want to see that again. The repercussions went on for years. People felt they had been rolled, which they had, and they were going to look for holes in the rules, and they found them," Dove said. Remember, he says, "you can stall in the Senate in lots of ways besides debate."

Filibuster reform needs to come with big gains in order to be worth such high costs. And so, historically, the Senate only considers major changes when the minority is obstructing something the majority really, really cares about. In 1917, it was a law that was a prelude to entering World War I. In the 1950s, 1960s and 1970s, it was civil rights.

What's so odd and interesting about Senate Majority Leader Harry Reid's threats to eliminate the filibuster on executive-branch nominees is that the impetus is the exact opposite: The majority is considering rules changes precisely because there's nothing more the minority can obstruct that they really, really care about.

These aren't usual times in the Senate. So far as Reid is concerned, Republicans have already killed pretty much everything else the Democrats might want to do. When he's been confronted with the argument that Republicans might bring everything to a stop if Democrats change the rules, I'm told Reid's reply is sharp: "And that would be different how?"

Consider the record. Republicans abandoned a budget deal in favor of the mess that is sequestration. Gun control failed. Student loan rates doubled. Republicans are promising another debt-ceiling showdown. And now immigration looks unlikely to make it through the House.

What exactly is left that Democrats want to get done and Republicans are likely to work with them to finish?

This is the problem for Senate Republicans right now: The intensity of their obstruction has cut their leverage. Increasingly, Senate Democrats are coming to the conclusion that there's no way for President Obama to have a successful second term working through Congress. Republicans, in their view, are simply too reflexively opposed to anything the president wants to do.

They've also come to believe that Republicans aren't slow-walking executive branch and judicial branch appointments because they think the nominees are unqualified, but because they want to make sure Obama can't effectively work his will through agencies or the courts. "More and more Democrats are convinced it’s an explicit strategy to deny him a successful second term," says one aide.

If you heard Reid and McConnell going at it on the Senate floor Thursday morning, it's that last piece they were arguing about. McConnell dismissed Reid's accusations of obstruction as a "fairy tale." He insisted that Republicans have been regularly clearing nominees, especially for cabinet-level nominations. "The facts are that since this president took office, the Senate has confirmed 1,560 people," he said. "The Senate has confirmed every one of the cabinet nominees that's been brought up for a vote." He rattled off all the nominees who've passed with overwhelming support.

Reid didn't challenge McConnell's numbers. In fact, he agreed with them. "We wait and we wait and we wait," Reid said. "And finally we get a vote. And then it's a big, overwhelmingly positive vote. Yes, because there was nothing wrong with the person to begin with." To Reid, that's precisely the evidence that the obstruction is a strategy to hobble Obama rather than the minority using its historic right to block extreme nominations.

Reid's litany focused on what precedes the votes Republicans eventually allow: Gina McCarthy, the nominee to lead the Environmental Protection Agency, was forced to respond to a record 1,100 questions in writing. The 15 nominees that Republicans are ready to let through have been waiting, on average, for around nine months. Republicans have tried to make the National Labor Relations Board and the Consumer FInancial Protection Bureau inoperable by delaying crucial appointments.

This, to Democrats, is the real problem: Republicans don't really object to the nominees. They object to government working well under the Obama administration, and they've come up with a strategy to stop it from happening. Reid made the point by imagining a baseball team that signs an all-star only to be told they can't play him for most of the year. "What would happen to that team?" He asked. "They would go on. They would perform just like President Obama has done, but they don't play to their ability. And that's ridiculous that that's where we are."

McConnell isn't going to be able to convince Reid and the Democrats that Republicans aren't working to obstruct the Obama administration's nominees. But usually, he wouldn't need to: He'd just need to convince Reid and the Democrats that changing the rules would do more to damage their legislative agenda than it would do to help Obama. But that's going to be a hard case to make.