Government can manipulate the stock market in the short term in the exact same way that companies can manipulate earnings.
Well here the causation probably runs the other way: when the stock market is higher, people think Obama is more likely to win.
If you mean that the Obama administration can try to manipulate the market to make themselves win the general election, um.......look at the graph for the 2 months prior to the 2008 election? If Bush was manipulating that market to make sure McCain lost that election, he did a fantastic job.
Also, government cannot manipulate the stock market in the way that companies manipulate earnings, because the government doesn't control the prices of stocks. A company does control its costs and accounting measures, so it's easy to manipulate earnings. The only way to manipulate stock prices is either creating news or trading stocks. That's hard to do.
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your 7 time champion, Link.