A question about the state of the U.S. economy posed to President Barack Obama by a Colorado local television reporter on Monday drew national attention across the Internet and cable talk shows -- and deservedly so."Your party says you inherited a bad situation," the reporter asked. "You've had three and a half years to fix it. What grade would you give yourself so far for doing that?"The answer from the president was typical Obama: a slight bob of the head and shoulders and then, "You know, I would say 'incomplete.'"That pretty much sums up the most important issue of the 2012 political season. Leaving aside the issue of who's to blame for our deep recession and slow recovery, what's uppermost on the minds of many Americans is how and when it's going to be over.The Bureau of Labor Statistics says the economy continues to add jobs (163,000 in July), but the unemployment rate has held stubbornly steady (8.3 percent in July). The bureau says 12.8 million Americans remain out of work, another monthly measure that has shown little movement this year.August employment statistics are scheduled for release Friday. Surprises happen, but there is little reason to believe the trend for the year so far has suddenly changed.That's Obama's No. 1 challenge as he addresses the Democratic National Convention and the nation tonight to accept his party's nomination for a second four-year term. He'll have to find a way to impart confidence in his handling of the economy if he is to shuck the "loser" label that opponent Mitt Romney and others hung on him repeatedly last week at the Republican National Convention.His likely line of argument followed immediately after he graded his work as "incomplete" in response to the Colorado reporter."But what I would say is the steps that we've taken in saving the auto industry and making sure that college is more affordable and investing in clean energy and science and technology and research, those are all the things that we're going to need to grow over the long term."How much substance he can put behind that statement, and how believable and appealing he can be, will only be known after he reaches the traditional "God bless" at the end of his convention speech.There are many other important issues Obama must and undoubtedly will address. None will be as crucial to his re-election hopes as the economy.