Four years ago this week, national polls showed Hillary Clinton leading Donald Trump by 3 percentage points.
By April 2016, Clinton showed a commanding lead. By July, Trump had edged ahead. By October, Clinton led again. After ballots were counted that November, Trump came out 2 percentage points behind in the popular vote, but won in the Electoral College with narrow victories in just the right states.
Since then, it has seemed wiser than ever to stay out of the prediction business.
Volatility is even more of a theme this year. Vermont's Sen. Bernie Sanders, who has been looking like a front-runner, leads Trump in one-to-one matchups. But he's as unapologetic a leftist as Clinton was a self-styled centrist.
National party committee members express skepticism that Sanders can win the general election. But some of them surely don't want him nominated, regardless of whether he can beat Trump. No Democratic insider is going to admit — at this point — that they might prefer to reelect an erratic GOP executive who seeks not just to defeat but delegitimize them.
Now that Joe Biden has won a big primary in South Carolina, the conventional wisdom of the current five minutes has shifted.
In January 2016, Sen. Chuck Schumer (D-N.Y.) said top Republican lawmakers believed that if Trump or GOP Sen. Ted Cruz were nominated, either would lose big in the general election and, in the process, would return Democrats to a U.S. Senate majority.
While Schumer may have reflected the momentary view of his colleagues, things didn't work out that way. Trump took office with both a GOP House and Senate behind him.
Now some mainstream Democrats warn that if their own anti-party establishment agitator wins the nomination, it not only could prompt a Trump landslide but return Republicans to a House majority.
Maybe so, maybe not. Just remember how the "smart money" got it wrong last time.
Another wild card is that for a president blessed with a strong economy, a united party and no new wars, Trump gets remarkably below-average presidential approval ratings.
On paper, he should look invulnerable. But Trump is deeply unpopular among important swathes of the population. At the moment, nobody can say for sure if this matters. That must depend in part on who will face him in November.
Frightening voters away from the Democratic Party is a constant strategy for the president, whose appointments, declared policies and rhetoric reflect nothing nonpartisan.
In Trump's Twitter rants, and in the speeches of Senate Majority Leader Mitch McConnell, even mainstream Congress members are predictably cast as crazed radicals.
Joe Biden, who pundits call "moderate," is described by Rudy Giuliani, Trump's lawyer, as in league with the likes of much-demonized philanthropist George Soros.
Constant polarization shows no sign of abating.
During this election campaign, many people will say “I have a theory … ” when they really mean, “I have a guess … ”
But no analysis, however sharp, is prophecy.
Think back only to New Year's. Nobody expected coronavirus to shake the world economy. How could that have been predicted? Will it trigger tougher times for the U.S.? Does anyone know for sure?
More than 55 years ago, in “The Times They Are a-Changin’,” Bob Dylan told a generation: "Don't speak too soon for the wheel's still in spin."
That's still sound advice.