Through JD Vance, Donald Trump's economic policies could outlive ...

The real-time reviews from the man who picked him were effusive: "JD crushed it!" Donald Trump posted on his Truth Social page about the man running to be his vice-president. 

While not everyone will agree in quite those terms, the debate was arguably JD Vance's best moment since he accepted the Republican Party's nomination.

It's been a rocky couple of months for him since then.

His previous politically tone-deaf remarks on "childless cat ladies" resurfaced and put him on the defensive. It was seized upon by two of the most powerful childless ladies in the world when they endorsed Kamala Harris for president: Taylor Swift and Oprah.

The senator from Ohio has also repeatedly stumbled on the campaign trail and appears to struggle in bread-and-butter retail politics, as best illustrated by his awkward interaction at a donut shop.

He came into the debate less popular than the Democratic candidate, Tim Walz. 

But Walz struggled in his biggest moment. He seemed nervous from the start, stumbled over his words, and did not appear ready for prime time.

Vance, though, rewarded the trust Trump had placed in him.

He looked the part: healthy, relaxed, and surprisingly more amiable than snarky.

He was articulate and managed to communicate Trump's policies more effectively than Trump did in his own debate against Harris.

While Trump was easily goaded by Harris into defending such inane topics as the crowd sizes at his rallies, time and again, Vance deftly pulled the debate back to topics he sees as Republican strengths, like immigration.

He had some weaker moments. Vance struggled to explain the party's position on abortion rights, and his failure to acknowledge Trump's 2020 election loss suggests that he's still scared of earning the ire of the former president.

Viewers gathered at watch parties in bars and pubs, like this one hosted by the New York Young Republican Club in New York City. (Reuters: Adam Gray)

But his robust defence of Trump's position on international trade was one of the most interesting aspects of this debate.

Vance was gushing: "For the first time in a generation, Donald Trump had the wisdom and the courage to say to that bipartisan consensus, we're not doing it anymore. We're bringing American manufacturing back."

He's right to suggest that, on this issue, Trump has transformed American politics.

For decades, America's political parties had gradually opened the country to freer international trade.

Almost all economists agree that lowering trade barriers leads to lower prices. That's a good thing for consumers.

But it's come at a destabilising cost, with many traditional American manufacturing jobs effectively moved offshore.

While American consumers, on average, might receive a small marginal benefit from a Chinese-made toaster being a couple of bucks cheaper, the American worker who loses their job when their toaster factory closes may be financially destroyed. The community that hosted that factory is hollowed out.

For the past eight years, Trump has campaigned effectively on that societal cost.

His message to the so-called "rust belt" states in the Midwest, which have felt the impacts most keenly, has been a promise to bring those jobs home.

Trump's preferred mechanism is tariffs on imports, which he slapped first on China but then extended to many other countries on a range of different goods.

Imposing a tax on those imports makes them more expensive, which is bad news for consumers buying those products but good news for American companies making the same products, because it makes it easier for them to compete.

Key trade partners were aghast the tariffs, and many implemented retaliatory tariffs on US goods. But if they were hoping Trump's defeat would see a reversion to the previous status quo, they were mistaken.

President Joe Biden has adopted a policy that seems equally sceptical of the benefits of international trade. He's continued the Trump-era tariffs on China and gone further. He's also prioritising workers over consumers.

Where the Democrats have gone even further is by directly supporting local industries with new government subsidies to support green energy projects and computer chip manufacturing.

Trump's response is to push for further corporate tax cuts for companies that make their products in the US while lobbing even higher tariffs on products coming from overseas.

It's a different mechanism, but Vance made clear that the Republicans were focused on supporting and protecting local businesses and no longer wedded to the orthodoxy of free trade leading to better outcomes.

This election is shaping up to be extraordinarily tight. If Trump wins, his power over the party will be near absolute.

But he has said that if he loses, he doubts he'll be running again. 

Vice-presidential debates typically don't have a major impact on election campaigns. (Reuters: Mike Segar)

That leaves 40-year-old Vance as the frontrunner to become the standard bearer for the MAGA wing of the party. He may have previously compared Trump to Adolf Hitler, but he now has the Trump seal of approval.

While Trump's primary season success speaks to his hold on the Republican Party, it's likely that traditional conservative Republicans will attempt to wrestle back control if the party is unsuccessful this year.

Those who support neoliberal economics, like free markets and trade, want their party back. Vance might be the biggest obstacle standing in their way.

Vice-presidential debates have never seriously impacted a presidential election, and although Walz would have disappointed many with his shaky and at times bumbling performance, there was nothing so egregious that it's likely to have shifted too many votes.

What may be more significant was Vance's authoritative control of the limelight. 

A sign that with him as the flag-bearer, MAGA control of the Republican Party may outlive Trump, and with it, an America that continues to shun free trade.