We've been tracking the "enthusiasm gap" between Democrats and Republicans for several months. But political analyst Charlie Cook breaks down the numbers within the numbers and shows why the president is in deep trouble unless he can reignite some of the passion felt by voters in 2008.

Just as Mitt Romney's challenge last week at the Republican National Convention was to connect on a personal level with voters and make them comfortable with the idea of him sitting in the Oval Office, President Obama's challenge this week at the Democratic National Convention is to reignite the flame-the passion among young and Latino voters that burned four years ago but is now just a smoldering ember.

Three demographic groups turbocharged Obama's 7-percentage-point victory over John McCain in 2008: young voters ages 18-29, Latinos, and African-Americans. Their influx changed the composition of the electorate that year, making it look quite different from the makeup of voters in 2000 and 2004. Whether the 2012 electorate looks more like 2008-or 2004, or 2000-is a very big deal for both Obama and Romney.

Among the 9,659 registered voters interviewed by the Gallup Organization's tracking polls Aug. 6-26, Romney and Obama were tied overall at 46 percent. But Obama beat Romney by 24 points, 58 percent to 34 percent, among voters ages 18-29 and by a whopping 32 points, 61 percent to 29 percent, among Latinos. In each case, the percentage who say they will definitely vote is significantly lower than it is among other demographic groups who view Obama less charitably.

Voters ages 65 and older favor Romney by a 15-point margin, 54 percent to 39 percent, and 86 percent of those in that oldest cohort say they definitely plan to vote, compared with just 61 percent of those ages 18-29. Romney has a statistically insignificant 1-point edge (46 percent to 45 percent) among those 30 to 49 years of age, but 80 percent of them say they will definitely vote. Among the 50-to-64 age group, Romney leads by 3 points, 48 percent to 45 percent, with 86 percent of that cohort saying they will definitely vote.

Even a fall off of 3-5% in turnout -- depending where the fall off was greatest -- could hand Romney several key states including Virginia, Colorado, and Florida.

Here's AT's Political Correspondent Rich Baehr writing at PJ Media today:

Assuming Romney wins Missouri, North Carolina, and Indiana - three states where he now has the lead - his Electoral College total would be 206. If Romney can win Ohio, Virginia, and Florida, he would be at 266. Iowa then puts him over the top. If Michigan is in play, as it seems to be, then Romney has a shot at 317 Electoral College votes, all the Bush states from 2004 except New Mexico, plus New Hampshire, Wisconsin, and Michigan.

In the RCP averages, Obama now holds the following leads in the tossup states: Ohio 1.4%, Virginia 0.6%, Nevada 3.3%, Wisconsin 1.4%, Michigan 1.2%, New Hampshire 3.5%, Florida 1.0%, Iowa 0.2%, and Colorado 1.6%. The states in which Romney leads plus those in which he trails by less than 2% total 307 Electoral College votes. Exclude Michigan, and the total is 291. Many of the battleground states have had no polls taken since the GOP convention, and Romney's numbers may improve from levels in those averages.

Of course, there will likely be a bounce-back  for Obama this week in Charlotte. Given voters' much greater familiarity with Obama than Romney, it is possible, however, that viewership will be down even more for the Democratic convention this year than for the GOP convention and the positive buzz for the president will be diminished, despite the best efforts of Obama's many media worshipers. This race has been close for months, and there is no evidence yet of a breakout by either candidate. The debates may offer the last chance for that.

Obama will try to connect with Middle Class white voters in his speech at the convention and try to cut into Romney's substantial lead with that group. Romney's strong showing with whites is fueling his surrge in Michigan, Iowa, and Wisconsin, putting those midwestern states in play and forcing the president to expend resources and time in states he won easily in 2008. A breakthrough in two of those states will probably mean a Romney victory.

It is not likely that the president can rekindle the magic with the young and Latino voters. They are already tuning him out and probably won't even be watching Thursday night when the president makes his pitch. But don't overlook Obama's massive organization where he will attempt to wring every last vote possible out of the electorate. Turnout among those groups may be down, but the question is how much, and can Romney exploit the enthusiasm gap and ride that momentum to victory.