In a 1994 episode of Seinfeld called "The Opposite," the hapless George Costanza, unemployed and living with his parents, decides that all of his instincts are wrong. So in every new situation, he announces, he's going to do the opposite of whatever his impulses tell him to do. Following this maxim, by the end of the episode he has a new girlfriend, a new apartment, and a job with the New York Yankees, which he obtains after berating George Steinbrenner in his interview.

Donald Trump might consider whether he needs to follow Costanza's lead.

There are still a few weeks left before election day, and there are no doubt more entertaining developments to come. But at this point, we may be able to say that Donald Trump is the worst presidential candidate in American history. Never before has a major party nominee assembled such a spectacular combination of impromptu screw-ups and strategic lunacy in a single campaign.

Let's take a quick look at what Trump is up to these days:

Fighting with Republican leaders.

Fighting with sympathetic ordinary citizens.

Complaining that everything from the polls to the debates to the entire election is rigged against him.

Not bothering to practice before the debates, when he'll be watched by nearly 100 million people.

Not bothering to mount a ground operation to get his supporters to the polls.

Responding to the release of a ghastly tape in which he brags about committing sexual assault not with anything resembling genuine contrition, but instead by dismissing it as "locker room talk" then making Bill Clinton's affairs the thematic centerpiece of his campaign.

Marinating in right-wing fever swamps to the point where he seems to think it's effective to rail at people like Sidney Blumenthal and Jonathan Gruber, whom most voters neither know nor care about.

Alienating moderate women, Latinos, and pretty much any key voting bloc he can't afford to lose.

Generally campaigning as though he'll win if he can just maintain the loyalty of guys wearing "Trump That Bitch" T-shirts.

There has quite simply never been a candidate like him. And I'm fairly certain that by next week we'll have a few more to add to the list. If you watch a Trump rally or check out his Twitter feed — pretty much the only form of campaigning he does — you'll see all of this on display. Between attacks on Paul Ryan (who remains the most popular politician in America among Republican voters) and lengthy rants on '90s-era scandals, Trump will literally read the results of bogus online polls off a smartphone to his adoring fans. Because if the Drudge Report's "poll" shows he won the debate bigly, that must be the truth.

"It is so nice that the shackles have been taken off me and I can now fight for America the way I want to," Trump tweeted Tuesday morning. At last! Now he can finally convince wavering voters why he's even more abominable than they thought.

You may be asking yourself: If this is all true, why is Hillary Clinton leading by a mere seven or eight points, and not much more? The answer is that polarization — or what we might better refer to as partisan sorting — has reduced crossover votes to a tiny proportion of the electorate. There are almost no conservative Democrats or liberal Republicans left, which is why in 2012, Barack Obama got 92 percent of Democrats' votes and Mitt Romney got 93 percent of Republicans' votes. Even with a candidate as, shall we say, unusual as Donald Trump, the proportion of Republicans who are willing to abandon their party — which means abandoning conservative policies and a Supreme Court majority — to vote for a Democrat or just not vote at all is going to be small.

That means that Republicans could nominate a rabid hamster and he'd get at least 35 or 40 percent of the overall vote ("I may not agree with Squiffles on everything, but I like the fact that he tells it like it is and will shake up the status quo").

Since Clinton will have the support of nearly all Democrats (who outnumber Republicans by a few points to begin with), losing just a small portion of GOP voters would guarantee defeat for Trump. But could he suffer a truly historic loss? The largest blowouts in recent history came in 1984, when Walter Mondale won only 41 percent of the vote; 1972, when George McGovern won only 38 percent; and 1964, when Barry Goldwater won only 38 percent. At this point, it's possible that Trump could be in that neighborhood. Some recent polls have shown his support dipping into the 30s, although there are still undecided voters, and he'll get at least some of their votes, not to mention the fact that Gary Johnson and Jill Stein are pulling more in polls than they'll probably wind up with.

On the other hand, what are the chances that there won't be another Trump scandal or two before this is all over? A new tape revealing even more odious behavior, another outburst that causes even more Republicans to unendorse him, a meltdown at the third debate, or some new kind of controversy we haven't even been able to imagine yet? Are the Democrats really out of opposition research material on him?

When that comes, it's possible that it could push Trump even lower than he is now. And just imagine if, in addition to running this mind-boggling campaign, he becomes one of the biggest losers in American political history. That would be something to see.