Democratic Sen.-elect Doug Jones (D-Ala.). (John Bazemore/AP)

Ding-dong, 2018 is finally here, and with it the chance for Democrats to take their archenemy, Donald Trump, down a peg. Talk swirls of winning the House of Representatives, even halting the juggernaut of conservative judges streaming through the Senate. Trump is so unpopular! Why, Democrats are more confident than I’ve seen them since . . .

Since Nov. 8, 2016.

The indispensable RealClearPolitics tracks trends in all sorts of poll results — including the average gap between the numbers of Americans who view President Trump favorably and unfavorably.

As of Dec. 27, the president was deep underwater, his unfavorables outpacing his favorables by 19 percentage points, 57 to 38. But look back to Election Day, Democrats, before salivating over Trump’s apparent weakness. Then, he was 21 points down in favorables, 58.5 to 37.5. Given margins of error, those are essentially identical findings. Our year of living crazily appears to have changed no opinions on the topic of Trump — which suggests to me that he might very well win again if an election were held today.

To achieve their dreams of an anti-Trump wave, Democrats have a lot of work to do. And to be honest, the normal rhythms of politics don’t necessarily encourage fresh thinking and diligence at this point in the cycle. Typically, midterm elections are the political equivalent of the Golden Globes: lesser occasions that serve as imperfect omens, soggy tea leaves that pundits can read for signs of bigger things to come. Do the Golden Globes foretell the Oscars?

Yes, unless they don’t.

Does an off-year election prophesy the next presidential contest?

No, unless it does.

This year ought to be different. This election has major implications; it is a reckoning, not just a windsock. It is the first national plebiscite after the earthquake. Trump's victory was a radical moment for the American electorate, something quite unlike the customary choice between the red crayon and the blue crayon — something more, even, than a sullen refusal to color inside the lines at all. A decisive turnout of key voters in key places shredded the entire coloring book, soaked it in diesel fuel and dropped a match.

The coming year offers the closest available thing to a do-over. Results in hundreds of local, statewide and federal elections will add up to a ring of dots that, connected, will mark a new set of political boundaries. Whether those new boundaries embrace Trump or wall him out will say a lot about the future of Trumpism in America.

Yet — and here's the tricky part for Democrats — making 2018 into a year-long referendum on Trump is a recipe for another Election Day shocker. Among other innovations, Trump has demonstrated the limits of the purely negative campaign. Between his own goofs and outrages and the points scored by his enemies in the last election, Trump sank in the polls to depths no normal candidate could survive. Nevertheless, it's his Diet Coke now filling the White House fridge.

The opposition needs to present a compelling alternative, one that appeals not just to coastal cities and college towns, but to the more centrist and even conservative audiences that vote in the nation’s dwindling swing districts and in the states hostile to Democrats on the 2018 Senate map.

To win the House, Democrats need to pick up at least 24 new seats, which in this age of precision gerrymandering is a much heavier lift than it used to be. Capturing the Senate is an even more formidable task, notwithstanding the recent unlikely win by Democrat Doug Jones in Alabama. Ten Democratic senators are defending seats in states Trump won. Even if all those seats are held, the party would need to find two more wins on a highly unfavorable map to make a Senate majority.

The opponents will not all be as loopy and creepy as Roy Moore.

To turn the tide of Trumpism, Democrats need candidates and policies that speak to voters in red states and red districts; winning the purple places, as they've done in Virginia and New Jersey this autumn, won't be enough. This will require wooing some voters who own guns, work for fossil fuel companies, shop at Hobby Lobby and eat Chick-fil-A — even attend churches where abortion is a vital concern.

The painful choice that faces partisans in a polarized time is whether to be true to an ideology or flexible in creating coalitions. Republicans made their choice in 2016 by embracing a candidate whose views on trade, diplomacy, human rights and a raft of other issues were far outside the GOP orthodoxy. They have conservative judges and a tax cut for their spoils.

Now Democrats must decide how big they are willing to make their own tent — understanding that Trump’s future may hang on their answer.

Read more from David Von Drehle's archive.