The Atlantic: We called five historians and political scientists to ask them which presidential election this one most resembles. Here’s what they said.

"The election that immediately comes to mind is 1968—particularly the negativity aimed at Lyndon Johnson and the direction the country was going in because of the Vietnam War. What most commentators miss is that Johnson’s resignation wasn’t just about the war. He also was facing a serious economic problem that I don’t think he knew how to resolve. Nations were beginning to indicate that they wanted gold for the dollars they were holding, and there was no way the country could pay that off. Johnson’s problem was in thinking that he could finance both the war in Vietnam and the War on Poverty, and it turned out he couldn’t finance both. Already you had the early signs of stagflation setting in that Richard Nixon finally had to deal with.

“Even so, Johnson’s approval ratings then were far higher than Bush’s are today. People were genuinely surprised when Johnson announced he wasn’t running, because he could have conceivably done so.

“All the negativity should have made for an easier victory for Nixon over Hubert Humphrey. When Humphrey started out, the negative attitudes toward him because of Johnson and because of the war were a lot like what John McCain faces today. But the election turned out to be quite close. That’s largely because Johnson—probably too late—halted bombing and initiated negotiations with North Vietnam. He did that in October. Some people believe that had the election occurred three weeks later, Humphrey might have pulled it out. Viewed in that context, there’s still hope for McCain. But his prospects certainly don’t look good.”...