On Wednesday, Economic Forecaster-in-Chief Barack Obama said, “I don’t think we’re in danger of another recession.” Shades of John McCain’s “The fundamentals of our economy are strong.”

On Thursday, the stock market – freaked out by Europe’s spiraling debt crisis and a shockingly weak Philadelphia Fed manufacturing report – plunged 4.5 percent. In an unintentional rejoinder to Obama, investment bank Morgan Stanley opined that the United States was “dangerously close” to falling back into recession.

When American presidents win reelection, they usually win by a heftier margin than the first time around. Narrower victories are rare, just three or four depending if you’re looking at the electoral or popular vote. When voters break against an incumbent, it’s usually fatal for the guy in the Oval Office. And right now, things are breaking bad for Obama. Really bad. Gallup has been pegging his approval rating right around 40 percent, even sometimes dipping to 39 percent. Regarding the economy in particular, Obama registers just 26 percent approval, his lowest rating ever and way down from a high of 59 percent in February 2009.

And it may be about to get a whole lot worse for the Obama 2012 campaign. The White House’s worst-case scenario for the economy on Election Day next year has become Wall Street’s baseline scenario. After looking at a string of weak economic reports and Europe’s growing fear of debt meltdown and contagion, JPMorgan – led by Obama pal Jamie Dimon – has just come out with a politically poisonous forecast.

The megabank now thinks the economy won’t grow much faster over the next 12 months than it did during the first half of this year — and that’s assuming Europe doesn’t go all pear shaped. It sees GDP growth at just 1.5 percent this year, 1.3 percent next year with unemployment at … 9.5 percent heading into the final days of the election season. “The risks of recession are clearly elevated,” the bank said. Here’s its reasoning:

Consumer sentiment has tumbled and household wealth has deteriorated. Survey measures of capital spending intentions have moved lower and the housing market shows little sign of lifting. Small businesses, retailers, builders and manufacturers all report a weaker business environment. Global growth has disappointed and foreign growth forecasts have been taken lower. In response we are lowering our projection for growth, particularly in the quarters around the turn of the year.

Team Obama had better permanently shelve any plans of running a “Morning in America” campaign. In fact, if a) the economic forecasts of Morgan Stanley, JPMorgan and Goldman Sachs are accurate, and b) voters behave as they usually do during bad economic times, then c) Barack Obama will be a one-term president. No president in the modern era has been reelected with the unemployment rate higher than 7.4 percent, much less two percentage points higher.

But Obama’s political folks are clever, far more than the guys who ran Jimmy Carter’s horrific 1980 campaign. And maybe the Republicans will nominate a candidate that scares Midwest suburbanites silly. Or perhaps Obama’s plan for “winning the future” will imbue the gloomy American public with a a bit more hope that whatever Republicans offer. Perhaps. But if Obama wins four more years with this economy, it will be almost as historic as his win in 2008.