US President Donald Trump has declared that he would pay every American adult a "Trump dividend" of $5 if Republicans retain control of Congress in the midterm elections in November.

"If the Republicans win, you win with us and get $5," Trump said during the Republican National Convention in Dallas, calling the promised payment the "Trump Dividend."

With about 270 million adults in the United States, such a payment would cost about $1.35 trillion. It would require congressional approval to implement, and the proposal comes at a time when the US faces an annual deficit of about $1.8 trillion and concerns about inflation.

Trump compared the payments to dividends that companies distribute to shareholders, referring to "our extraordinary economic strength and success."

During his speech, which lasted about an hour and 45 minutes, Trump declared that he had completed "the greatest two years in the history of the presidency," placing himself at the center of the campaign for the midterm elections.

However, within an hour, Vice President JD Vance appeared to be trying to clarify Trump's proposal, suggesting that the payments would not go to the wealthiest Americans.

Vance also said the funding could be covered by revenue generated through U.S. tariffs. However, the estimated cost of a program of $5 per adult would be far higher than the amounts the U.S. has collected through tariffs.

Trump has repeatedly expressed concern that the president's party almost always loses seats in Congress during midterm elections.

"We're going to change that. There's no reason for that," the US president declared.

Republicans are facing a tough race to maintain their narrow majority in the House of Representatives, while the Senate, previously considered safer for Republicans, is also expected to be contested.

Trump also faces dissatisfaction among some of the electorate over the rising cost of living and the war with Iran.