According to news stories, the Trump campaign fired pollsters who allegedly leaked polling results that show President Trump performing poorly against Joe Biden and Bernie Sanders in battleground states. Regardless of the accuracy of the story, what can polling really tell us now? At this time in 2015, polls were showing Hillary Clinton 17 points ahead of Donald Trump. According to Gallup, Ronald Reagan's approval rating was about the same as President Trump's at the same time into his presidency. In November 1984, a year and a half later, Reagan won a historic landslide victory, winning 49 of 50...