When Senate Minority Leader Mitch McConnell speaks, I’ve learned to listen. It’s not that the jowly Kentuckian is such an inspiring orator. Quite the opposite, in fact. With his sleepy drone and laconic rhythm, he’s the rare politician who usually seems to be boring even himself. Nor is he the back-slapping, yarn-spinning sort that frequently prospers in the Senate. McConnell’s got all the warmth of an ice floe.

But then, McConnell doesn’t need to be inspiring or jocular. Shouldn’t be, in fact. What he’s saying isn’t inspirational or funny. It’s grim and divisive. And that’s why it’s so important. In a city split between liars and idealists, McConnell is the rarest of all things: an honest cynic. He’s the only powerful politician in America willing to tell you how Washington actually works, and that’s why he needs to be heard.

McConnell’s first brush with radical truth-telling came in October 2010, when he told National Journal that “the single most important thing we want to achieve is for President Obama to be a one-term president.” McConnell quickly qualified his remarks, although he never quite apologized for them.

Nor should he have. McConnell wasn’t articulating a radical new theory of politics. He was telling us how he and his party were already voting. Consider the dozens of elected Republicans who, at one time or another, supported an individual mandate for health-care reform, cap-and-trade for carbon emissions and tax cuts for stimulative purposes. Over the past three years, almost all of them have renounced their former views. Unless you understand McConnell’s argument, you can’t understand their actions.

A year ago, I broke down a vote on unemployment benefits by looking at senators from states with higher-than-average and lower-than average jobless rates. It was totally random. Then I reshuffled the votes by party. The randomness disappeared. Senators aren’t voting their consciences or their states. They’re voting their party, which means they’re voting their party’s incentives. Democrats won’t prosper unless Obama prospers. And Republicans can’t succeed unless Obama fails.

But I don’t want to leave you with the impression that McConnell understands only partisanship. He’s a shrewder analyst of bipartisanship than anyone else in Washington.

Many here understand a “bipartisan bill” to mean one with ideas from both parties. On deficit reduction, for instance, it would mean Democrats give in on spending cuts if Republicans give in on tax increases. McConnell understands it to be one with votes from both parties. That’s why he can keep a straight face while saying something like “President Obama needs to decide between his goal of higher taxes, or a bipartisan plan to address our deficit. He can’t have both.”

McConnell is right. Voters don’t spend their time conducting detailed analyses of legislation and neither — let’s be honest — do the media. Instead, both groups take their cues from political leaders. If the Republicans call a bill partisan and refuse to support it, the bill gets reported as partisan no matter its content.

Obama wasn’t lying when he talked about the many Republican-friendly tax cuts included in the stimulus, the many conservative ideas that formed the core of the health-care law and the trillions in GOP-demanded spending cuts that were added to his budget proposals. But McConnell wasn’t lying when he said that Republicans cared more for defeating the president than for anything else — and that “anything else” includes passing policy initiatives they had long supported. After all, you don’t beat Obama by partnering with him on his agenda. You beat Obama by turning him into a polarizing, partisan figure. And you do that by unilaterally denying him bipartisanship.

The president sold himself as the great post-partisan hope, the leader who could bring comity and peacefulness to a town riven by partisanship and rancor. When McConnell refuses to come to bipartisan agreements with Obama, he damages Obama’s brand. More than anyone else, McConnell has been responsible for his failure, and key in demonstrating how little any one leader can do to change the tone in Washington

There’s supposed to be a curb on this sort of behavior: If you don’t participate in the legislative process, you don’t get anything out of the process. Here’s McConnell’s most important insight: That’s wrong. Withholding minority-party votes forces the majority party to hand its most moderate members — and the most moderate members of the other party — an effective veto, which drags the legislation substantively to the center, and in the current situation, to the right.

Health-care reform was more conservative than it would have been if more Republicans had been willing to support it. The stimulus was smaller than it would have been if conservative senators had been willing to back the whole in return for concessions on the parts. It turns out that a partisan political strategy results in more bipartisan policy. The opposition can have its cake and eat it, too. That doesn’t leave much reason for it to be bipartisan, of course. But for a minority party that wants to defeat a president who sold himself as a unifier, that’s a plus.

“We worked very hard to keep our fingerprints off of these proposals,” McConnell told the Atlantic in January, “because we thought — correctly, I think — that the only way the American people would know that a great debate was going on was if the measures were not bipartisan.”

McConnell was, of course, correct. More people should have been listening.