CINCINNATI - Seventeen days before he faces Republican challenger Mitt Romney on a Denver debate stage, President Obama is keeping his preparations for the first encounter largely a secret, while his aides publicly vow to keep details of the process a close hold.

"Three things I know for certain," Obama campaign spokeswoman Jen Psaki told reporters today on Air Force One. "One, he will be at the debates participating; two, he's not debated in four years; three, the longer format of the debate, or the shorter format of the debate is not always conducive to someone who gives longer substantive answers."

"We have no plans to read out or confirm how he's preparing for the debate," she added.

The approach contrasts sharply with the very public discussion of Romney's preparations by him and his aides, who are banking on the debates as the next flashpoint in a tight race and opportunity to pull ahead.

The Republican nominee spent three days in Vermont earlier this month conducting mock debates with Ohio Sen. Rob Portman, who has been tapped to play Obama. Romney's schedule this month has included several more hours of debate preparations behind closed doors, including this past weekend where Portman was again on hand for more practice.

Romney also made sure to tell reporters this weekend after a day off the trail that much of his downtime was spent "studying."

"They've made clear that his performing well is a major factor," Psaki said of Romney. "We can go through this process every day, but we're not giving any details on our preps."

Obama had no weekend public events, remaining in the White House with family, reading and getting briefings on the situation in the Middle East, aides said.

While the campaign has been coy about preparations, Psaki sought to somewhat downplay expectations for Obama's performance, acknowledging that the three October debates pose a real challenge.

"While Mitt Romney has done 20 debates in the last year, he [Obama] has not done one in four years, so there's a challenge in that regard," Psaki said.

She also acknowledged that the debate format - requiring short answers of less than two minutes to each question in an uninterrupted 90-minute session - might not be favorable for Obama, who likes to give longer responses.

The first presidential debate takes place in Denver Oct. 3. The candidates also face off in Hempstead, N.Y., Oct. 16, and in Boca Raton, Fla., Oct. 22.

ABC News' Emily Friedman contributed to this report.