Take a deep breath. Exhale. Repeat, until the anxiety attack passes. Then go vote, and soon our long national nightmare will be over.

FBI Director James B. Comey’s “October surprise” decision to cast last-minute shade over Hillary Clinton, based on emails he and his agents had not even read, was appallingly unfair. But there’s nothing to be done about that now — and no reason to believe it will change the fundamental shape of the race, which has been remarkably consistent. Donald Trump remains on track to lose, and the question is by how much.

The only way he could possibly win is if Democrats and other “Never Trump” voters stay home on Election Day out of complacency. Comey’s intervention should have eliminated that possibility. Look what happened Friday after his letter about the emails was made public: The Dow Jones industrial average reacted as if to a natural disaster, plunging about 150 points before slowly recovering when it was learned that this latest twist grew out of the Anthony Weiner investigation.

In other words, the thought that Trump might actually be elected touched off a momentary panic. Then the realization that this remains quite unlikely coaxed investors down from the ceiling.

Nothing concentrates the mind like a glimpse into the abyss.

Democratic presidential candidate Hillary Clinton campaigned in Cincinnati on Oct. 31. (The Washington Post)

To state the obvious, this is not a normal election. Democrats have nominated the first woman to head a major-party ticket, a controversial figure with vast experience who has been on the national stage for three decades. Republicans have nominated the worst candidate in modern history, a know-nothing narcissist who lies constantly, treats women like possessions and appeals not to the better angels of our nature but to the worst bigotry and resentment. One candidate surely would be a competent president, perhaps a very good one. The other would be an unmitigated disaster.

That has to be the bottom line: Who’s going to be sitting in the Oval Office, making the life-or-death decisions that come with being the most powerful individual on Earth? Do you want a life-long public servant with an encyclopedic grasp of the issues, or a buffoon guided only by his own prejudices?

The fact that more than 40 percent of voters will choose Trump anyway, regardless of his many disqualifying faults, is depressing but should not be defeating. Our political leaders will have the task of finding some way to knit the nation back together. But the immediate imperative is keeping our fate out of Trump’s hands.

In that sense, this election has never really been about Clinton, her history, her husband or her emails. It has never even been about her many exceptional qualities or her legions of enthusiastic supporters, as evidenced by the fact that she won nearly 16 million votes in the primaries — about 2.5 million more than Trump. Next Tuesday’s vote is primarily about the fact that she stands between us and the grave risk of a Trump presidency.

Fortunately, most voters seem to understand. In the RealClearPolitics average of national polls, since the two candidates wrapped up their nominations Trump has held a lead over Clinton for all of two days — July 29 and 30, when Trump was enjoying a boost following the Republican National Convention. Since then, Clinton has held a clear lead — sometimes bigger, sometimes smaller, but uninterrupted.

Likewise, in the swing states that will decide the election, Trump has never shown signs in the polls of coming close to the kind of clean sweep he would need to win an electoral majority. Clinton could lose both Ohio and Florida — which have gone back and forth — and still win comfortably. Moreover, she has put traditionally Republican states such as Arizona, North Carolina and perhaps even Georgia into play.

The ideal outcome would be a Clinton landslide in which the country thoroughly and unambiguously rejected Trump and all that he stands for. The unfortunate outcome of Comey’s announcement may be to make this less likely. Before Friday, Trump was flailing and his supporters were becoming demoralized as defeat seemed certain. Now Trump has a closing argument and the crowds at his rallies can dream once more of stunning the political world.

But those who want to see Clinton win and those who want to see Trump lose also should be newly energized and motivated. They have a clear advantage in support. They have a vastly superior get-out-the-vote operation. They have far more viable ways to assemble the necessary 270 electoral votes.

So stop obsessing. Breathe. And vote.

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