Writing about political analysis, The Post's Michael Gerson observed earlier this week that "all good lessons . . . are eventually overlearned, especially by once-burned political commentators."

He suggested that the commentariat may be so afraid of being proved wrong again that they are now underestimating some of President Donald Trump's weaknesses. And the Wall Street Journal's William A. Galston recently pointed to two critical factors that will determine the 2020 outcome: whether last year's record voter turnout carries over to next year and how much of the "blue wall" of states such as Pennsylvania, Wisconsin and Michigan − all of which Trump won in 2016 − he can hold on to this time around.

I am a believer that in U.S. politics, what is supposed to happen tends to happen. We tend to re-elect our presidents. And we certainly have a history of giving a party two terms in the White House. Only once since World War II has either party,  irrespective of the candidate running for office, won just one term. And that was in 1980 when Jimmy Carter had all the symptoms of a losing incumbent. George H.W. Bush lost his re-election, but he was elected immediately following another Republican administration, a la Ronald Reagan. Through this lens, it would appear the incumbent president should win re-election in 2020. But the other way of getting at what is supposed to happen requires that we look at Trump's strengths and weaknesses.

One of Trump's weaknesses is hard to quantify yet glaringly obvious. Specifically, it is not unusual for a president to go through a period of sagging in the polls only to emerge invigorated by the negatives of their opponent and buoyed by the voters' sense of fairness about letting the president finish the job. But in Trump's case, he might, in fact, deny himself the usual cycle of deflating job performance ratings and gradual rehabilitation that is often afforded to incumbents. Trump's negatives are obvious, and the source of many of his problems comes from his own tweets and insulting behavior. It is safe to say Trump has broken new ground in his ability to offend. It is habit he cannot tame. And in his eventual opponent's favor is the apparent law that Trump's objectionable qualities are the gift that keeps on giving − he renews his negatives daily, sometimes hourly. There is never a chance to forget what you do not like about Trump.

And let's remember that Trump won in 2016 by drawing an inside straight. He was not elected in a landslide but quite the opposite. Narrow wins in states such as Michigan and Wisconsin made the difference for his campaign. Today, at least anecdotally, it is hard to see where Trump has built any new support. In fact, having spent the past holiday weekend in the Florida Panhandle, I saw plenty of instances where Trump has lost support, and there has even grown a social stigma associated with being a Trump supporter where there was not before. When one talks to Trump supporters, there is almost always a caveat, a sheepish grin or just the "can't believe it's come to this" shake of the head. There is rarely anything resembling enthusiasm.

I remember when, in 2012, a lot of Republicans thought that disdain for President Obama would sufficiently motivate Republicans and independents to turn out and vote down a second term. Already, many Trump boosters seem to think that, as bad as he is, the notion that a Democrat would be worse is enough to propel the president to re-election. That assumption by Republicans may prove as faulty next year as it did in 2012.

So, can Trump run a campaign in which he does not remind voters, every day, what it is about him that they find lacking − at best − or destructive and offensive at worst? His victory in 2016 had more to do with Hillary Clinton underperforming what should be expected of an average Democrat candidate than it did any magic Trump brought to the race.

Only a fatally flawed Democratic candidate next year could repeat that set of circumstances. On the flip side, if the Trump-Pence strategy for 2020 is just more of the same, that augurs well for a solid Democratic opponent, someone who can mute the left's calls for socialism and dampen liberals' frightening plans for our society and economy.

Maybe then, Trump would beat himself. 

Ed Rogers is a political consultant and a veteran of the Ronald Reagan and George H.W. Bush White Houses and several national campaigns.