Perceptions of the economy this summer will shape the outcome of the 2012 election. By David Morris, Deputy Managing Editor June 13, 2012 As anxiety about the economy mounts, the 2012 presidential race is tightening. Where it was once President Barack Obama's election to lose, Republican challenger Mitt Romney is closing the gap.SEE ALSO: Economic Issues That Will Drive the 2012 Election Obama can still pull out a win in November, but the prospect is less probable than it was just a few weeks ago. Some of his support is fading amid dismal job creation numbers, tepid GDP growth, concerns about Europe and a nervous stock market. But there are some positives as well, including falling prices for gasoline, signs of life in the housing market and an uptick in new orders for manufacturers. How the economy fares this summer will be crucial in determining whether Obama wins another term or becomes the fourth incumbent to lose in 36 years. (For those of you keeping score at home, the incumbents who lost in that period are Gerald Ford in 1976, Jimmy Carter in 1980 and George H.W. Bush in 1992.) Advertisement The key, come Labor Day, is how voters perceive the economy. After that, no matter how the economy performs, the perceptions aren't likely to change. If perceptions are that the economy is doing OK, incumbents win, even if the overall numbers are soft. If the perceptions are bad, they lose. It's a simple formula, but it stands the test of time in elections in which major foreign policy crises don't intervene. The 1992 race between George H.W. Bush and Democrat Bill Clinton is a good example of how the actual numbers don't matter that much. The economy was perking along by Election Day, and had actually turned in a positive direction earlier in the year. But perceptions never caught up with reality, and Clinton, with a lot of help from third-party candidate Ross Perot, sent Bush into early retirement. This summer, these key events will shape perceptions of the economy: Advertisement The June 17 election in Greece. If Greece stops using the euro currency -- and it seems likely it will, either on its own or by being forced to by other governments -- the global economy will take a hit if chaos ensues. The size of the hit will be determined by the extent of the mess. The June 18-19 G-20 summit in Mexico, where leaders of the world's biggest economies will focus on Europe. A possible Obama-called summit with German Chancellor Angela Merkel. It's a risky move, and not all of Obama's advisers endorse the idea. But it could help the president if the talks delay Greece's departure from the euro or prompt European leaders to ensure that problems don't spread to Italy or get much worse in Spain. The Commerce Department's July 27 report on GDP. There are two sets of numbers to watch: The size of second-quarter growth and the government's review of data from the past three years. A downward revision of past growth would help Romney. Advertisement The government's monthly employment reports for June, July and August. A sustained surge in new jobs is unlikely this summer, but a one-month jump isn't out of the question. At the moment, five of six states that will be key to the outcome of the election -- Ohio, Virginia, Colorado, Iowa and New Hampshire -- have unemployment rates below the 8.2% national average. Only Florida's 8.7% is higher than the U.S. number. Not coincidentally, Obama is doing better in the first five states than he is in Florida. As summer approaches, this feels like a tipping point. The economy can take the race either way. There isn't much the president or the challenger can do but sweat out the season. Jerome Idaszak and Kenneth R. Bazinet Jr. contributed to this story.