In January 2009, the month Obama was sworn in, there were 133,561,000 total non-farm payrolls in the U.S. -- a tick higher than the 133,245,000 payrolls recorded in July 2012, according to the Bureau of Labor Statistics.
At the current rate of hiring, Obama could easily pass into positive net jobs territory before the election, voiding this particular talking point entirely. But by most other, less tendentious readings of the data, Obama passed into positive job creation territory months ago -- and the claim that "he hasn't created one single net new job" at this point rests on blaming Obama for the loss of public sector jobs Republicans support cutting, and also rests on holding Obama accountable for jobs that were lost in January before he took office on the 20th.
When Obama took office, the economy was shedding jobs at a terrifying clip. Monthly job losses didn't turn into gains until about a year into his first term, or about six months after his stimulus plan kicked into gear. But you don't need to absolve Obama for responsibility for the first year or half-year of his presidency to put him unambiguously in positive territory.
By February 1, 2009, less than two weeks after he was sworn in, the number of jobs had dropped precipitously to 132,837,000. Using that figure, the economy's added just over 408,000 jobs during Obama's presidency.
Using a different metric that excludes only public sector jobs -- which have taken a significant hit in the last three and a half years, notwithstanding Republican claims that the government's grown rapidly under Obama -- he crossed into positive territory earlier this year.
According to BLS, the private sector employed 110,985,000 people in January 2009. The private sector hit bottom in February 2010 with 106,773,000 employees. By July 2012, that number had grown to 111,317,000.
Politics doesn't require opponents to interpret data fairly, and Republicans will probably use this line until it either becomes invalid or we reach Election Day, whichever comes first. But like when Democrats chide Romney for posting weaker job growth while governor of Massachusetts than all but three states it requires using convenient, if not appropriately contextual numbers.
BLS will release its initial August job growth estimate the morning after Obama's Thursday night convention keynote address. A low figure will color next-day coverage of his speech. But it should also indicate clearly if Obama will cross into positive territory across all metrics before the election.