Trump has repeatedly said he fears the election will be rigged and has made a hard-line stance on immigration a centerpiece of his campaign. His latest provocative claim comes as Trump and Clinton are preparing for their second debate, a town-hall style confrontation Sunday night. It's a critical moment for Trump , who after a rough performance in last week's debate is tasked with showing he can stick to his campaign message and steer clear of comments likely to alienate moderate voters.