Ahead of President Trump’s plan to impose sweeping tariffs across the globe this week, his administration is weighing a new round of emergency aid to farmers, who are likely to be caught in the middle if America’s trading partners retaliate.

The early discussions offer a tacit acknowledgment that Mr. Trump’s expansive tariffs could unleash financial devastation throughout the U.S. agricultural industry, a crucial voting base that the president similarly tried to safeguard during his 2018 trade war with China.

While the president has not announced any details of an aid package, his advisers have signaled in recent days that he could follow a playbook similar to the one he used in his first term, when he directed billions in payments to farmers who saw their exports to China plummet amid a trade war with Beijing.

Such a rescue package ultimately proved expensive, with the government shelling out about $23 billion after China imposed high retaliatory duties on soybean, corn, wheat and other American imports beginning in 2018. That money came from a fund at the U.S. Department of Agriculture, a portion of which can be used to respond to emergencies, including trade disputes.

Brooke Rollins, the agriculture secretary, said last week that the administration may look to offer emergency aid to farmers, telling reporters that Mr. Trump had asked her to “have some programs in place that would potentially mitigate any economic catastrophes that could happen” in a global trade standoff.

But the price tag this time could prove even higher, since Mr. Trump has threatened to target many countries, including American allies like Europe, Canada, Mexico and Japan. The potential scope of their collective retribution could inflict deeper, more lasting harm on American businesses.