Joe Biden in Philadelphia on May 18. (Matt Rourke/AP)
Opinion writer

Crucial to President Trump’s political mystique is maintaining the illusion that he is perpetually winning, basking in adoring crowds, in total control of events and dominating his foes on every front — no matter how dramatically he must falsify reality to keep that impression alive.

And so, even though Trump’s tariff wars are growing so unhinged and unpopular that members of his own party are rebelling against them, the president’s political team is leaking word that he’s going on offense bigly on trade, against his No. 1 perceived enemy of the moment: the Democratic front-runner Joe Biden.

But now, I’m told, Biden is gearing up to take Trump on over the issue, opening up a new front in an area that is central to Trump’s reelection hopes, and one that some Democrats have shied away from.

In a statement sent to this blog, the Biden campaign sharpened its criticism of Trump on trade, hammering his agenda as “erratic and impulsive,” while claiming it’s imposing untold “economic pain” on ordinary Americans via a “Trump Tax” and diminishing our country’s standing in the world.

According to new reporting by Axios, the Trump campaign privately sees Biden as a threat to him in the industrial Midwest, which will be pivotal to reelection, because “internal Trump polls have Biden substantially ahead in the Rust Belt.”

So the plan, Axios reports, is for Trump allies to begin hammering Biden as a “free-trading globalist who would undo the president’s trade agenda.” They will do this by raising questions, such as: “What specifically will Biden do with China? Will he lift President Trump’s tariffs? How does Biden defend his past advocacy for NAFTA?”

The Biden campaign is hitting back. In a statement sent my way, Biden deputy campaign manager Kate Bedingfield said this:

We can’t trust President Trump to look out for American workers, because for all his bluster, he never does. Just look at the record: The trade deficit is larger than when Trump took office, he’s forced labor to take a back seat in his dealings with China, and he’s alienated our allies who also suffer from China’s trade abuses. Instead of delivering results, Trump is asking American farmers and American families to bear all the costs of his trade war. His administration’s erratic and impulsive approach to China is causing families economic pain.

Joe Biden would rally our friends and allies to hold China accountable, so that working families and farmers don’t pay an extra Trump Tax. Biden would also restore our standing in the world on Day 1, advance our security and prosperity, and deliver results for all Americans -- not just the well connected.

What’s noteworthy here is the effort to tie Trump’s trade failures to a broader failure of Trumpian nationalism. The New York Times reports that the Trump campaign believes his continued trade war with China could be a political plus, letting Trump “cater to his political base” while “heading off any Democratic attempts to outflank him as the great protector of American workers.”

But there’s no reason to presume in advance that Trump has the upper hand on this issue. Unlike in 2016, voters have now seen the concrete results of Trump’s nationalist trade bluster — and the genuinely held worldview underpinning it — colliding with the complex realities of international diplomacy and the global economy.

That collision has rendered Trump vulnerable on trade — even in the Rust Belt. A new Detroit News poll of Michigan finds that Trump trails most Democratic hopefuls, some by large margins. Notably, 47 percent of Michigan voters say Trump’s China policies are bad for the state, vs. only 26 percent who say the opposite.

Crucially, among Michigan union households, opposition climbs to 55 percent, and independents oppose the policies by 2 to 1. Those groups likely include many of the blue-collar white and Obama-Trump voters Democrats must win back. Meanwhile, recent Quinnipiac polling found that in the industrial Midwest states, Trump’s trade policies are underwater.

What’s more, Democrats have a good argument to make against Trump on trade: that his nationalism in practice has proved reckless, rooted in rage and whim; alienating to allies; and counterproductive, and that Democrats would restore sober, reality-based international cooperation to the center of our trade agenda.

Such an approach might be employed, say, against China’s currency manipulation practices, as progressive economist Dean Baker points out. “A multilateral approach would likely mean getting the European Union, the United Kingdom, Japan and the United States to negotiate a rise in the Chinese yuan of some targeted amount against the dollar,” Baker told me.

By blasting Trump’s agenda as “erratic and impulsive” and by vowing to rally allies against China and to “restore our standing in the world,” the Biden campaign is beginning to road-test such an argument.

Biden takes hits from the left on trade

All this comes as Biden might himself be vulnerable on the issue. Progressives such as Bernie Sanders and Elizabeth Warren have staked out aggressive positions against trade deals such as NAFTA and the Trans-Pacific Partnership, both of which Biden supported.

Sanders recently ripped Biden for expressing skepticism that China is going to “eat our lunch,” arguing that Biden downplayed the Chinese threat to U.S. workers and vowing himself to offer a trade agenda that is in their interests.

A Biden campaign source tells me that Biden offered this in the spirit of trying to disarm Trump’s demagoguery of the China threat, which is the groundwork for a case for a more rational, multilateral approach in place of threats and bluster.

Biden has knocked Trump’s trade war with China, and we should expect a more comprehensive substantive blueprint from him in coming months.

The differences between the primary candidates on China will be litigated in the primaries, of course. And so will Biden’s position on NAFTA, which he has since defended, though some polls suggest it might not matter a great deal to Democratic voters.

But this debate is all to the good. Whoever the Democratic nominee is, he or she may unite the party around an agenda built on multilateral cooperation against China, higher wage, labor and environmental standards in trade deals, and serious investments in displaced U.S. workers. Such a debate will ultimately put Democrats in a stronger position against Trump in an area where he’s weaker than all the bluster suggests.

Read more:

Catherine Rampell: Just a few of the reasons that Trump’s Mexico tariffs are deeply stupid

Greg Sargent: Trump’s worldview is failing spectacularly. Several new studies illustrate how.

The Post’s View: Trump’s tariffs on Mexico are the kind of erratic act the Constitution is meant to prevent

Greg Sargent: Trump is staking reelection on one of his biggest lies

Jennifer Rubin: How Joe Biden gets under Trump’s skin