DALLAS, Texas—President Donald Trump on Wednesday night cast his second term as “the greatest two years in the history of the presidency,” rallying voters to support Republicans in the upcoming elections at a historic midterm convention in Dallas. Trump promised to issue a $5,000 dividend to every adult citizen if Republicans keep their majority in both the House of Representatives and the Senate. “Your vote will decide whether our country stumbles at the starting gate of the next 250 years or surges forward and never ever looks back,” Trump said as he began his remarks. “Vote Republican, and we will...