Watch: Barack Obama slams Trump during the Democratic Convention

Obama said he disagreed with a pessimistic vision of the country’s prospects laid out at the Republican convention last week "America is already great," Obama insisted, rejecting Trump's campaign slogan, "Make America Great Again." "America is already strong. And I promise you, our strength, our greatness, does not depend on Donald Trump" "We're not a fragile people. We're not a frightful people.....We don't look to be ruled"