The first presidential debate will be shown live here on CNN.com and on CNN apps for iPhone and iPad at 2300 GMT, 0000 CET, 0700 HKT. Edit your own clips, see which topics spike on the Twitter barometer, and join the debate.
Denver (CNN) -- To win in November, Mitt Romney must emerge from his first debate with President Barack Obama as the leader on this campaign's defining question: Which candidate do voters trust more to handle the economy?
"He has to paint a compelling picture of a better economic future and why he can lead us there and President Obama can't," GOP pollster Whit Ayres told CNN when asked to define Romney's paramount debate challenge.
Democratic pollster Peter Hart made the same point but in more colorful language: "If Romney loses this issue, then he is toast."
Yes, there are other important challenges for both the Republican challenger and the Democratic incumbent as they share the debate stage for the first of three encounters.
Romney, for example, must pass a test all challengers face when appearing side by side with an incumbent: look and sound like a credible alternative, like a president. The GOP standard-bearer also needs to quiet the jitters among Republicans who see the presidential campaign trending in a direction they worry could hurt down-ballot.
For the president, some aides and advisers worry most about coming across as smug, or too dismissive, of criticism of his economic stewardship.
His burden also includes the challenge of showing how the next four years would be different without helping his challenger's case that the approach of the last four years was misguided.
But given the state of the race, very competitive but with an Obama advantage in several of the most important battleground states, veteran strategists in both parties agree the heavier burden in the first debate is on Romney.
And they agree his overriding challenge is to seize the upper hand in the economy argument. The candidates enter the Denver debate tied on that key question.
Our new CNN/ORC International poll asked likely voters which candidate would better handle the economy. Obama was the choice of 49%, Romney of 48%.
Pollster Ayres said the key in winning over undecided and persuadable voters is for Romney to make the case the president's economic proposals are "government-driven" and that Romney's rely on small business and the broader private sector as engines of growth.
The president's response, according to aides familiar with his debate preparations, will be twofold: cast Romney's proposals as little or nothing new, a throwback to favor-the-rich GOP policies that the president argues contributed to the economic ditch, and raise questions about Romney's understanding of, and empathy for, the struggles of working- and middle-class families.
The format should offer voters a clear contrast:
• Three segments on the economy
• One on health care
• One on the role of government
• And one on governing leadership and style.
As always, there is the debate season sideshow known as the expectations game.
It can be fun to watch, especially when high-profile surrogates like New Jersey Gov. Chris Christie ignore the Romney campaign talking points and instead promise a campaign-changing debate performance.
Fun, but in the end meaningless. The surrogates and spinners aren't on the debate stage. Or on the ballot.
This is about Obama and Romney, their first of three debates a test of whether the challenger can make a persuasive case that he has a better economic plan or the incumbent can sell voters on staying the course.