As they look towards the general elections, it’s clear that President Obama and GOP frontrunner Mitt Romney both face very specific problems. Romney’s problem is one of personality: no candidate in the modern polling era with personal favorability ratings as low as his has ever won the presidency. Obama doesn’t have a popularity problem, but he does face some trouble with the economy: no incumbent president has ever won re-election with unemployment rates as high as they are likely to be in November. Carroll Doherty, associate director for Pew Research Center, and Kenneth C. Davis, author of “Don’t Know Much About History,” explain what is behind these numbers.