President Donald Trump promised every adult US citizen a $5,000 payment if Republicans win both chambers of Congress in November, dangling a cash incentive as he urged supporters to treat the midterm elections like another presidential race.

Speaking at the Republican Party's midterm convention in Dallas on Wednesday, Trump unveiled what he called the "Trump dividend."

"If the Republicans win, you win with us, and you get $5,000. It will be called the Trump dividend," he said.

He said the proposed payments would be "very much like a successful company will do a cash distribution to its shareholders."

The dividend "must be spent in the United States of America," he said.

Trump did not explain how the payments would be funded.

The proposal would cost about $1.35 trillion if every adult received the payment, Kent Smetters, a professor of business economics and public policy at the Wharton School and faculty director of the Penn Wharton Budget Model, told Business Insider.

Vice President JD Vance later said the payments would not go to the wealthy.

If the checks excluded wealthy Americans, the cost would fall to about $1.15 trillion, assuming a household income cap of $400,000, Smetters said.

Trump has floated similar ideas before.

Last year, he proposed $2,000 "tariff dividend" checks for low- and middle-income Americans, funded by tariff revenue.

The proposal failed to gain traction in Congress, with several Republicans arguing the money should instead go toward reducing the national debt, and no payments were ever made.