Some of his rivals scoffed. Election-law experts have questioned whether the move would be legal (Yang’s campaign has said lawyers have assured them it is). But after the Sept. 12 debate, his campaign raised $1 million in less than a week. More than 450,000 people have signed up to enter the contest — which means hundreds of thousands of email addresses for campaign mailing lists. He told reporters after the rally the chosen families, selected at random, would be announced next week.