The 1978 United States Senate election in Illinois took place on November 7, 1978. Incumbent RepublicanUnited States SenatorCharles H. Percy ran for re-election to a third term in the United States Senate. Percy was opposed by Democratic nominee Alex Seith, an attorney who had been appointed to several local government positions. Though Percy had been expected to coast to re-election over Seith, a first-time candidate, the election quickly became competitive. In the last few days of the campaign, a desperate Percy ran a television advertisement that featured him apologizing and acknowledging that, "I got your message and you're right." Percy's last-ditch effort appeared to have paid off, as he was able to edge out Seith to win what would end up being his third and final term in the Senate.