The Democratic Party would be wise to get inside Mitch McConnell's head. It is a dark place, to be sure, full of furious resentments, but it is amazingly disciplined and organized so that nothing matters but certain cherished goals. One of them is to make President Trump think he's in charge of the Republican agenda. The other is to implement the Republican agenda.

The fruits of this discipline are everywhere to be seen. The federal judiciary is being transformed. The Supreme Court has already lurched to the right. The 13 circuit courts are swiftly following. Trump's nominees get occasional Democratic support, but they almost never get Republican opposition. What Trump once said about shooting someone on Fifth Avenue applies to his judicial nominees as well: He could nominate the man he just killed and the GOP would support him.

McConnell is the great enabler. Trump has insulted him. He has berated him. He has zinged him on Twitter and harangued him over the phone. But the Senate majority leader, like the Little Engine that Could, just keeps on going. He will not resign over principle because he has none. It is best in Washington to travel light.

This is a lesson for the Democratic Party. Its sacred obligation is to deny Trump a second term. It is not to turn the county socialist in any way nor to institute Medicare for everyone nor to award reparations to the descendants of slaves. Whatever the virtues of these programs, they present nearly insurmountable political problems, and they would, more likely than not, help re-elect Trump.

A number of Democratic candidacies fall into the same category. Pete Buttigieg is an exciting new face, intellectually keen and dynamic, yet he's also gay and married, and while I would exult in a picture of the two under the White House Christmas tree, I don't think it would be embraced by portions of America. Mayor Pete is young, only 37. He can wait. First things first, and the first thing is to defeat Trump.

But that's not what a considerable number of voters feel. I call them Lemming Democrats, and they were fingered in a Washington Post article about a new poll that went online over the weekend: "(Joe) Biden's campaign is centered on the idea of being the most likely to defeat President Trump in a general election. But slightly more Democrats and Democratic-leaning adults prefer a candidate whose positions are closest to theirs, rather than the one who seems most electable." The emphasis is mine.

Those italics contain more than enough hemlock to kill the Democratic Party's chances of doing in Trump. These are the lemmings, smugly heading to the sea consumed with virtue and deluded by a misreading of history. In the past, it was possible to argue that the difference between the two parties amounted to the difference between Tweedledee and Tweedledum or, to update matters, one Kardashian or another. But that is not the case for 2020. One statistic ought to settle the matter: By the end of April, the Post's Fact Checker had found that Trump had "made more than 10,000 false or misleading claims." The man lies with every breath; he is unfit for the presidency.

I want to ask the Lemming Democrats if nominating a gay man to the White House is worth risking the re-election of a president who cannot tell the truth. Is supporting a socialist worth a second term for a chaotic autocrat who resists the notion of climate change, who would deny women the right to abortion, who presents America to the world as a nation that resists family planning of any kind? Is support for reparations worth the victory of a president who insists on the glory of Robert E. Lee and whose embrace of the Kremlin is not simply puzzling but revolting? The foul odor of collusion and corruption clings to Trump. He's a criminal whose crime is yet to be found.

Mitch McConnell must open his morning paper and chortle. He is a man who has never really stood for anything and here, to his puzzlement and delight, are all these Democrats willing to risk the re-election of the worst and most dangerous president in U.S. history. If that happens, the courts will be universally conservative and McConnell will have reversed just about every program Barack Obama conceived. Progress will halt, and the environment will be despoiled.

Addison Mitchell McConnell Jr. will go down as the most effective majority leader in American history. He will, though, have had plenty of help.

Richard Cohen's column is distributed by the Washington Post News Service.