Mike Murphy is strategic adviser to Republican Voters Against Trump, co-host of the “Hacks on Tap” podcast with David Axelrod and a veteran of six Republican presidential campaigns.

After three hard years of fuming over President Trump, it has been a reassuring summer for Democrats. The Biden campaign had a strong convention, capped by a best-of-career speech by Joe Biden. Party fundraising is surging, and the polls look excellent. But a good campaign is a paranoid campaign, especially 70 days before an election.

So even though I think Biden is likely to win, I’m spending my time worrying about how he could lose. Here is what could go wrong:

Biden could still fumble the definition war. Opinions of Trump are etched in stone; we love him or we hate him. Right now, the haters are in the majority and polls show the country is itching to fire him. Trump could try to improve his image, but his braying tone and clumsy tactics never change. Don’t count on the Donald to heal himself. But if Trump is well defined, Biden and Kamala Harris are not. Heading into next week, the Trump strategy is brutally simple: change the focus from firing Trump to fearing Biden and Harris.

The Republicans will pound away at Biden and Harris with all the golden oldies that worked for them before. I was there when Republicans did a nasty new paint job on the once shiny Michael Dukakis. Whether they want to or not, Americans will be watching Fox News-style programming next week as the GOP tries to recast “Pop and Momala” as wild tax-and-spenders, enemies of private health insurance, dangerously soft on illegal immigration, destroyers of the suburbs and purveyors of vote fraud.

Democrats may scoff at this, but these attacks will take a toll. (And truth be told — a rarity in GOP politics these days — the ideological critique isn’t imaginary; Harris in particular has a notably liberal voting record.) Barack Obama used the same define-him-first playbook to end Mitt Romney’s White House hopes in 2012.

The debates worry me, too. So far, the election has mostly been Trump vs. covid-19, and the virus has won every round. Biden’s terrific convention speech smashed Trump’s dire hints about Biden’s mental acuity, but now that he’s a proven home-run hitter, Biden will face much higher expectations. As a Motor City native, I greatly enjoyed Biden’s new video with his classic Corvette. Now get back to debate prep, Joe.

One more worry. I fear a black-swan scenario based on the most reliable force of all: human nature.

We know covid-19 is the true special feature of this election. It has crushed the president’s poll numbers. It has hurt millions of Americans, flattened the economy and made the electorate fearful and uneasy. The fatigue we all share is powerful, draining, exhausting; Americans desperately crave some good news.

Which means you can count on our cornered and unrestrained president to try to manufacture some. He’s already tried with phony cures including old malaria drugs, Clorox and the healing power of ultraviolet fish tank cleaning lights. But in a few weeks, Dr. Trump may “discover” a far more powerful elixir: Tens of thousands of patients are already in advanced trials for experimental vaccines. Whatever the ultimate outcome of these trials, it is certain that murky, highly preliminary news will leak.

Even a whiff of promising results, regardless of how premature they might be, will spark a surge of euphoria. The breathless media of our digital age will erupt. A cure is on the way! Markets will rocket higher and businesses will rush to open, as a huge wave of relief envelops a country sick of wearing masks. It’s all based on our understandable hunger for something good to happen.

This could make for an interesting October.

Trump will move fast to exploit this moment with the full power of his office. Whether any of it is scientifically true will be irrelevant to Trump. It will be also be irrelevant to many voters; as every dodgy operator knows, people just want to believe; be it a Bernie Madoff scam, a magic diet book, a Trump University hustle or any other of the cons, large and small, in human history. Trump, of course, understands that all too well.

I still think Biden beats Trump. I’d bet money on it. But not too much money. Only about 7 or 8 percent of the vote is really in play. Some will be convinced that Biden and Harris are too risky a choice. And if only half of the rest feel the cure craze and change their minds, everything can change. Don’t underestimate manias. The most famous example comes from wealthy 17th-century Holland. As most people know, in one particularly speculative moment, the price of a tulip exploded from virtually nothing to the price of a house. How long did it take for reason to go out the window? About 75 days.

It was probably a crazy time. But what would you call this?

See you in November.

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