During a long speech at a Republican convention in Dallas, Texas, Donald Trump sought to revitalise his conservative base, defending the unpopular war in Iran while trying to keep control of Congress in the November midterm elections by promising cash to every adult.

Trump strongly defended the Iran war, predicting victory and linking it directly to lower oil prices — before suggesting the strategically vital Strait of Hormuz should be renamed after him.

"Food prices and almost every other item are rapidly going down. And by the way, oil will be going down as soon as we win the war with Iran, which is taking place right now," Trump said.

But Trump appeared to acknowledge the war had taken a toll on the US economy. "We were doing great," he said, before turning to his economic advisers and telling them, "I hate to do this to you." He then explained that he had felt compelled to launch the conflict because Iran was perhaps "two, maybe three weeks away from having a nuclear weapon."

Trump also echoed other Republicans at the convention stirring up what he said was a wave of communism threatening the United States.