President Donald Trump, center, and Republican congressional members celebrate Wednesday...

President Donald Trump, center, and Republican congressional members celebrate Wednesday the passage of the tax bill on the South Lawn of the White House. Credit: Bloomberg / Andrew Harrer

There are two key narratives going on in America right now. The one that rings truer in 10 months will likely determine the results of the 2018 midterm elections.

The first encompasses all things anti-Donald Trump, the substantive and the petty: his demeanor, Russia, sexual assault allegations, tweets, volatility, lies, profits as president, big hair, small hands, fragile ego, Big Macs and Diet Cokes . . . The list goes on.

The second narrative goes something like this: “You know I’m no fan of this guy, but . . . ”

Positive stock market news or improving employment statistics finish the sentence.

Throughout 2017, conversation No. 1 dominated by 1,000 decibel points. The operative political question for 2018 is whether narrative No. 2 will overtake its rival in the coming months.

If it does — and it’s very possible — expect Republicans to hold both the House and Senate next year. The GOP will almost certainly lose seats in swing suburban districts, but the sky might not fall all the way to the ground. Acid-tongued political strategist James Carville tells us why, however crassly: It’s “the economy, stupid,” he told an at-first-disbelieving nation in predicting Bill Clinton’s 1992 upset win over President George H. W. Bush.

The Ragin’ Cajun’s doubters were many at the time, and you couldn’t blame them. The idea of a Democratic victory seemed preposterous just months earlier. In March 1991, at the end of the first Persian Gulf War, Bush held an 89 percent Gallup Poll approval rating, the highest ever. In the end, Clinton beat Bush by nearly 6 percentage points in a three-way race.

It was the economy, stupid — in that case, a struggling one.

The federal tax overhaul might kick the economy into sustained GOP growth levels of between 3 and 4 percent annually, as Republicans are optimistically projecting. Things already were looking up before the tax cuts were passed, with GDP up for three straight quarters in 2017. The true effects of the Republican tax cuts aren’t expected until after 2019; if the economy is cooking next October, Republicans will be able to say to voters, “You think this is great, just wait till next year.”

That’s a powerful message.

It’s said that a week can be like a year in politics, and that’s been proved true time and again. Things arise out of nowhere to alter the trajectories of candidates and nations.

With Trump in the White House, multiply that possibility by 10. Federal indictments could be handed up at any time in the Russia probe, for example, ensnaring people as close to Trump as Trump himself. That, or hard evidence emerging about past sexual misconduct by the president, could spell lights out for the GOP in ’18.

But say no more indictments happen, or that Trump is personally cleared in special counsel Robert Mueller’s probe. These could relegate Trump’s never-ending outbursts to mere background noise for many, with talk of the economy bubbling to the foreground. The prevailing narrative in ’18 could become, “Trump is Trump — just ignore him. He’s good for the economy.” Indeed, one feels that conversation already taking hold.

William F. B. O’Reilly is a consultant for Republicans.

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