With the Democratic National Convention in full swing, a number of party leaders are attempting to boost President Barack Obama's re-election effort by asserting that 4.5 million new jobs have been created during his term.

Obama himself has recently claimed more job growth in the past 27 months than President George W. Bush created"during the entire seven years before this crisis."

"Despite incredible odds and united Republican opposition, our president took action, and now we've seen 4.5 million new jobs," San Antonio Mayor Julian Castro said in his keynote address at the DNC on Tuesday night.

That statistic was echoed by virtually all of Tuesday night's speakers, including first lady Michelle Obama, Massachusetts Gov. Deval Patrick and Chicago Mayor Rahm Emanuel, who previously served as Obama's chief of staff.

However, CNN fact-checked that claim and found it to be "not the whole picture." Instead, CNN found that there has been a net increase of just 300,000 nonfarm payroll jobs since Obama took office. And if you count government jobs, there are actually 400,000 fewer people working today than in January 2009.

When Democrats use the 4.5 million jobs number, they're referring to jobs created after the economy bottomed out in January 2010, one year after Obama took office. That time frame excludes the worst job losses, which took place in 2009, and which many Democrats argue were the result of Bush policies.

CNN concludes: "The figure of 4.5 million jobs is accurate if you look at the most favorable period and category for the administration. But overall, there are still fewer people working now than when Obama took office at the height of the recession."

Still, a historical analysis of job growth percentages shows that Obama still fares better than some recent presidents. As of July, Obama is averaging +0.84 percent annual job growth in his term. That places him ahead of Bush, who saw +0.51 percent growth in his first term and -0.84 percent in his second term. Obama is also tracking better than George H.W. Bush, who presided over +0.69 percent growth during his one term in the White House.

However, Obama's job growth percentages trail far behind those of some other recent presidents, including Bill Clinton (+2.60 percent and +1.60 percent), Ronald Reagan (+1.75 percent and +2.53 percent) and even Jimmy Carter (+2.30 percent).