President Donald Trump used the Republican Party’s first midterm convention to justify the Iran war rather than trying to put it behind him, as escalating violence and spiking oil prices loomed over the elaborate Trump-centered showcase in Dallas. In a speech billed as an opening argument for the peak campaign season, he defended his record and encouraged supporters to vote as if he were on the ballot. He also debuted a new enticement, promising to reward Republican congressional majorities by giving every American a $5,000 dividend to spend within the country.