The 1968 Democratic National Convention in Chicago was not a peaceful event.Bettmann/Getty Images Philip Klinkner, Hamilton College It’s just over six months until Election Day. The president faces a tough fight for reelection. His approval rating has cratered below 40% in the polls, his party is divided over a foreign war, and a bipartisan chorus declares that he’s no longer up to the job. Polls show him running neck and neck with the likely Republican nominee. Faced with this grim situation, the president decides to put country before his own political ambition and declares he won’t run for …