As we’ve seen in the current GOP campaign for president, candidates rise and fall in the polls with more unpredictability than the stock market. This type of drama has played out countless times before in campaigns. Months of hard work, coupled with a great performance in a debate or a unique policy stance can boost a candidate to frontrunner status. But a moment of indiscretion or an awkward speech can bring a candidate’s campaign crashing down. Here are five presidential contenders who appeared on their way to their party’s nomination before disaster struck.