Forget the October surprise. The unpredictable, vote-swinging shock to electoral politics that materializes every presidential campaign could take place just four days before the election — when the October jobs report is released on November 2.

The fluctuations in the wavering national employment market have already come to dominate the race for president, dealing President Barack Obama's reelection effort a serious blow this week. The key figure comes in a monthly report by the Bureau of Labor Statistics — which estimates how many jobs were created in the prior month, as well as the unemployment rate. And the first Friday of each month has become primetime for political posturing, with various campaigns, candidates, and surrogates jockeying to spin the numbers in their favor.

But the October 2012 report, which will come out the Friday before Election Day, could drive the national conversation in the final days of the campaign — and make up the minds of crucial, undecided swing voters. In both 2004 and 2008, exit polls indicated that about 10 percent of the electorate decided on a candidate in the last week of the campaign. A lackluster October report, like the one that came out last Friday, could be the winning data point in Mitt Romney's campaign to discredit President Obama's economic policies. Alternatively, better-than-expected numbers could convince fence-sitting voters to stay the course.

Tony Fratto, the former Bush administration Treasury Department and White House spokesman, sees the final pre-election jobs reports as potentially being decisive this year.

"I think marginally attached voters, ones not paying a lot of attention right now, will begin to make up their minds in that convention/post-convention period," said Fratto, now a managing director at Hamilton Place Strategies, who also said the previous two reports would set the crucial narrative. "And if they're basing their votes on economic conditions, then those two jobs reports could be decisive."