President Donald Trump made an unscheduled appearance on the White House South Lawn Friday morning, exactly one hour and 13 minutes after the Commerce Department announced the U.S. economy grew at the impressive rate of 4.1 percent in the second quarter.

“These are great numbers,” he said. “We’ve accomplished an economic turnaround of historic proportions.”

Sure, some of this was Trumpian hyperbole. But it’s a show he can take on the road to help preserve Republicans majorities in the House and the Senate this November. Because there’s enough substance in the numbers and in the nearly 3 percent growth rate for the five complete quarters he’s been president that a salesman as good as Trump can sell the success.

Democrats were left to grumble about the rich benefiting most, and the mainstream press pointed to farmers hurrying silos of soybeans to China ahead of looming tariffs. But others recognized the seriousness of 4.1 percent growth. The Twitter feeds of House Minority Leader Nancy Pelosi (D-Calif.), and potential presidential candidates like Sens. Cory Booker (D-N.J.), and Kamala Harris (D-Calif.), were silent on the numbers — apparently operating under the theory that if you don’t have something mean to say, don’t say anything at all.

Sure, some of this was Trumpian hyperbole. But it’s a show he can take on the road to help preserve Republicans majorities in the House and the Senate this November.

Meanwhile, President Barack Obama’s Council of Economic Advisors Chairman Jason Furman, a Democrat whose business isn’t politics, chose not to deny the facts. He tweeted: “Big surprise: the underlying data for Q2 is even better than the headline 4.1% annual GDP growth rate.”

The president can help elect Republicans with the economic numbers because the 2018 midterms are going to be all about Trump. Just like the 2010 midterms, during which Obama admitted Democratic candidates experienced a “shellacking,” was all about him.

Trump dominates the news through his daily tweets, outrageous statements and personal charisma. Whether you think the Trump presidency is a 14-car pileup or the Fourth of July fireworks on the National Mall, you simply can’t take your eyes off it.

This means Trump will effectively be on the ballot in every congressional district and in every state where there’s a Senate race — and as long as he keeps talking about the economy, it’s a good place for him to be.

Sure, his 2016 election win was about a lot of things that aren’t always prominent, like immigration and cultural change. But according to the massive national exit poll, the economy was still the foremost issue in voters’ minds. Fully 52 percent named the economy as the “most important issue facing the country,” compared to only 18 percent who said terrorism, 13 percent who went with immigration and another 13 percent who chose foreign policy.

The thing you still need to sell in an election is the economy — and right now for Republicans, that’s looking like a pretty high-quality product.

And it’s not just a glancing association, either. Whether one thinks Trump’s prescriptions are the right ones or not, he has a record of at least trying to help the economy. He signed a massive tax cut. His administration has been busy rolling back regulations that businesses say are have been hamstringing them for years.

The biggest short-term threat to continued economic growth, tariffs, were partly mitigated by last week’s deal with the European Commission to put the duties on hold — and even increase some European imports of U.S. goods — while negotiators try to work out a long-term agreement. Tariffs on Chinese goods remain a problem, but Trump can probably argue, with some resonance, that China has been cheating the United States on trade policy and stealing U.S. technology for years, and something’s simply got to be done about it.

Meantime, for many voters, particularly those in red states like Montana, North Dakota, West Virginia and Indiana where Democratic senators are imperiled, the rise of the progressive vanguard and its talk of vast new federal entitlements and higher taxes will provide Trump with the perfect foil to make his case. If Trump can go to these states, as well as swing states and districts, and declare that Democrats want to maintain economic growth by instituting socialism, Republicans may be in good shape indeed.

No doubt there are pitfalls ahead for Trump. The first estimate of third quarter GDP is scheduled for release October 26, just 11 days before Election Day, and a bad number could certainly rain on Trump’s campaign trail parade. But right now, economists expect that number to come in at around 3 percent. That means, politically speaking, the next report on economic growth is more likely than not to be bad news for Democrats.

A 4.1 percent economy is not just a tool Trump can use on the campaign trail to boost Republicans. It’s a weapon he can use to slay Democrats. Trump, being Trump, will deploy all kinds of rhetoric, some of it necessary to help bring out his base. But if he is disciplined enough to make the economy his headline, he could well be dealing with a Republican Congress for at least two more years.

Keith Koffler is the editor of White House Dossier and the author of "Bannon: Always the Rebel."