Speaking at a party convention, the US president gave no details on how the plan would work or where the money would come from.
Watch: BBC North America editor Sarah Smith looks into whether Trump's promise stands up
US President Donald Trump says he would offer every adult American a $5,000 (£3,700) payout if Republicans win both chambers of Congress in November's midterm elections â a plan that would cost more than a trillion dollars.
The offer was made in a speech at the party's first-ever convention in the middle of a US presidential term.
He gave no details on how it would work or be funded â saying only that the money would have to be spent in the US. Vice-President JD Vance has linked the plan to the revenue that Trump has raised for the US government using tariffs.
Democrats labelled it an "empty promise" and others questioned whether such a pledge was legal or feasible.
It may be the first time a US president offered such a payout to Americans, in the context of an election year plea to get out and vote.
The idea drew raucous applause at the convention and Trump seemed to relish the moment.
There are nearly 270 million American adults, meaning a $5,000 payout would cost the US government some $1.3 trillion.
Questions have begun to be raised about whether his plan is feasible â especially as prices rise in the US, partially as a result of the war that the US and Israel started with Iran in February.
Iran's retaliation has included attacks against US bases and allies in the Gulf â but crucially it has largely closed the Strait of Hormuz, through which about a fifth of the world's oil and liquefied natural gas used to transit.
The blockage has caused fluctuations in oil prices worldwide and Trump has faced pressure from his party to end the war.
On Wednesday, the US president warned his supporters that the war would not end until after the midterms and that oil prices would not come down until then.
He made the comments ahead of his speech in Texas, repeating it at the convention where he argued that short-term economic pain was worth it to prevent Tehran from developing nuclear weapons.
Watch: Trump says US adults will get $5,000 if Republicans win midterms
Trump's long speech at the Republican convention in Dallas, Texas, touched on the core of the conflict â the impact on Americans' standard of living. His pledge to increase their spending power drew raucous applause in the hall.
Reporting synthesized and verified under Nexvoro.tech editorial guidelines. Full primary records referenced via BBC World.
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