Donald Trump's latest tariff deadline arrives tonight, with potential new duties starting tomorrow morning on America's top three trading partners: Canada, China, and Mexico.

It's a threat that Trump has partially delayed once before — and administration officials are already hinting could be pared back. If Trump follows through on even a sliver of his many upcoming promises, it could match or surpass the economic toll of his entire first term.

The Tax Foundation estimates that Trump's 2018-2019 tariffs shrank US GDP by about 0.2 percent. The proposed tariffs this week against just Canada and Mexico are projected to surpass that, the group said, even setting aside all-but-certain retaliation and Trump's moves against China.

What Trump is pledging this week are 25% duties on Canadian and Mexican imports following a 30-day pause. He also has said a second round of 10% duties on Chinese imports are planned to up the blanket tariffs on that nation to 20%.

Andrew Harnik via Getty Images

The duties could come into effect at midnight ET. Trump is likely to give an update on his plans at 1 pm ET when he is set to appear at the White House for an investing announcement.

Trump's latest tariff deadline comes in a context of Trump decision-making on the economy that appears to be weighing down both the investing and consumer outlook in the United States.

"The economy appears to be gagging on the uncertainty created by the haphazard economic policymaking happening in DC," Moody's Analytics chief economist Mark Zandi said in a recent post. he listed a range of factors including "tariff wars, DOGE cuts to jobs and government programs and agencies, and deportations [that] are sowing confusion, which puts a pall on investment, hiring and spending."

Still, Trump recently insisted that tariffs "will indeed go into effect" as he and his aides focus largely on their fentanyl-focused rationale this week — saying "drugs are still pouring into our Country from Mexico and Canada at very high and unacceptable levels."

The focus on fentanyl comes as Trump and his aides also tout dramatic drops in border crossings — the other major stated rationale for this week's move — but with Trump claiming those changes are "mostly due to us."

A growing economic cost

Underlying the trade tensions is a market recognition that Trump may often be blustering when he talks trade but also that following through on even a small portion of his promises will have wide-ranging effects.

The Tax Foundation calls Trump's 2018-2019 tariffs "one of the largest tax increases in decades" — and those duties were largely focused on China.

Those moves, the group estimates, reduced the long-run US GDP by 0.2 percent and lowered employment by the equivalent of 142,000 full-time jobs.

Trump's promises are much more wide-ranging this time. He has already followed through on one China-specific pledge, slapping 10% duties on Chinese goods in early February over the drugs and migration issues.

Those duties alone, the Tax Foundation estimates, are set to shrink the US economy by about 0.1 percent if left in place.

But even if Trump eventually pushes this week's deadline, another looms close behind with 25% tariffs on steel and aluminum set to take effect on March 12.

A recent Goldman Sachs (GS) research paper on the issue noted that if Trump drops this week's threat and follows through on that second threat — and then does nothing else but keep the tariffs in place — it would be "roughly equivalent to all of the tariff hikes from the first Trump administration."

And plenty more is still possible. Trump has launched Commerce Department investigations into products such as semiconductors, copper, automobiles and pharmaceuticals for potential new duties.

Just this past weekend, Trump added timber to the list with a new investigation set to get underway there.

Trump has also recently promised 25% duties on the European Union without specifying exactly when that might come into force.

And then waiting next month is what Commerce Secretary Howard Lutnick calls "the big transaction": reciprocal tariffs that could begin to be implemented on a wide array of nations and goods themselves starting on April 2.

All told — charged former Trump communications director turned outspoken critic Anthony Scaramucci to Yahoo Finance this week — "I don't think this sort of blanket approach is the right way to do it, and I think he's [Trump] is going to put us into a recession."

'A fluid situation'

This week's deadline comes after Trump agreed to the pause last month following talks with Mexican President Claudia Sheinbaum and Canadian Prime Minister Justin Trudeau.

But Trump and his aides have promised that no more delays are in the offing and all three targeted nations have also signaled detailed plans to implement wide-ranging and creative retaliations in the case that Trump follows through. 

Canada could potentially target key sectors in GOP-run states like Florida orange juice or Kentucky bourbon, and China is set to further target the agriculture sector.

As for the duties themselves, Lutnick said Sunday that tariffs are set to go into place but that the levels could change in what he called "a fluid situation."

"There are going to be tariffs on Tuesday on Mexico and Canada," Lutnick said Sunday on Fox News. "Exactly what they are, we're going to leave that for the president and his team to negotiate."

Lutnick was announced by Trump as the leader of his administration's trade and tariff efforts but the weekend comments are reflective that the authority Trump is set to rely on this week is largely a unilateral one.

The duties would be enforced using a 1977 law called the International Emergency Economic Powers Act that endows the President with wide-ranging authority to act without even the minimal delays of things like a Commerce Department review.

Ben Werschkul is Washington correspondent for Yahoo Finance.

Every Friday, Yahoo Finance's Rick Newman and Ben Werschkul bring you a unique look at how U.S. policy and government affects your bottom line on Capitol Gains. Watch or listen to Capitol Gains on Apple Podcasts, Spotify, or wherever you find your favorite podcasts.

Click here for political news related to business and money policies that will shape tomorrow's stock prices

Read the latest financial and business news from Yahoo Finance