Clark, who has no experience in politics, instantly emerged as a front-runner following his late entry into the race. Political observers say the former NATO commander is likely to draw fire from the other White House wannabes during the two-hour debate.
On the eve of the debate, Clark offered the first glimpse at his domestic agenda, saying his policies are part of a promise to protect America from both economic and foreign threats. Clark's strategy: Counter his inexperience in politics by presenting even his pocketbook initiatives through the prism of his 30-year military career.
"Protecting the country in the 21st century requires more than a strong military. It requires a strong economy that generates jobs, economic growth, and the revenues we need to defend American lives and property — wherever they are in the world," Clark said in an address at a park along New York's East River, across from a soon-to-close sugar refinery.
Only eight days into his campaign, Clark has emerged as a threat to the field's top-tier candidates because of his military experience, an Internet-driven grass-roots organization and a solid political team comprised of veterans of the Clinton-Gore administration.
The debate offers Clark's rivals their first chance to slow his momentum.
Sen. John Kerry of Massachusetts said Clark will have to answer for his past support of Republicans Richard Nixon and Ronald Reagan.
"It's for Democrats to judge how they feel about people's lives and history," Kerry said. "But while he was voting for Richard Nixon and Ronald Reagan, I was fighting against both of their policies."
Kerry spoke after accepting the backing of the International Association of Firefighters, the latest in a string of endorsements he picked up this week.
Clark, who toyed with both parties after leaving the military in 2000, publicly declared himself a Democrat for the first time this month. By contrast, Kerry said, "I'm confident that a lifetime of being a progressive, fighting Democrat will make a difference in this race."
Clark spokesman Mark Fabiani fired back: "The only reason Senator Kerry wants to discuss how Gen. Clark voted 25 years ago is that Sen. Kerry himself apparently lacks a strong message about the future."
Former Vermont Gov. Howard Dean told ABC he was surprised that Clark voted for Republicans. Asked if Clark was a true Democrat, Dean replied, "I think that we have to find out about that."
If Clark's speech on Wednesday was any guide, his debate strategy will be to frequently mention his Army career and sprinkle his remarks with military metaphors while promising a "New American Patriotism." The slogan captures his promise to be the one candidate who can criticize President Bush's foreign policies without looking soft on terrorism.
"Some ask, 'How can you criticize the president at a time of war?'" said Clark. "I answer: 'How can you not?'"