LOS ANGELES (KABC) -- An exclusive Eyewitness News nationwide poll conducted by SurveyUSA shows that Donald Trump would beat all Democratic presidential candidates if the election were held today.According to the poll, Trump would narrowly defeat Hillary Clinton 45 percent to 40 percent in a head-to-head matchup. Sixteen percent were undecided.Against Bernie Sanders, Trump wins 44 percent to 40 percent.And against Joe Biden, Trump wins 44 percent to 42 percent.