The former president, speaking in Denver, posed a hypothetical question in which he seemed to suggest that that the Democratic Party was making a mistake in choosing Obama as its presidential nominee.

He said: "Suppose for example you're a voter. And you've got candidate X and candidate Y. Candidate X agrees with you on everything, but you don't think that person can deliver on anything. Candidate Y disagrees with you on half the issues, but you believe that on the other half, the candidate will be able to deliver. For whom would you vote?"

Then, perhaps mindful of how his off-the-cuff remarks might be taken, Clinton added after a pause: "This has nothing to do with what's going on now."

The comments are unlikely to be taken as an innocent mistake by those Democrats who continue to be angry with the former president for, they say, not supporting the Illinois senator wholeheartedly, if not implicitly undercutting him.

The controversial comments came just hours before Sen. Hillary Rodham Clinton (N.Y.), the former first lady and principal rival to Obama, was due to speak from the convention podium.

Democrats concerned about what the former president might say when he addresses the Democratic convention Wednesday night would likely have cringed at his remarks Tuesday to a group of foreign dignitaries.

The former president talked about the importance of a politician being able to deliver on his promises following an electoral victory and how voters factor in that ability to deliver when picking their candidate.

During the contentious and at times nasty nomination battle between Clinton and Obama, the Clinton campaign repeatedly pushed the question of whether Obama, a freshman senator, had the experience or the ability to deliver on his promises if elected. Clinton, they argued, was more suited to do so.

The former president devoted much of his sometimes-rambling remarks to solving the global energy crisis and the need to address climate change.

But time and again he returned to his great love of politics, noting that it was more than the closeness and intensity of the nomination battle between his wife and Obama that piqued his interest this year, but the "infusion of cash from small amounts by Internet donors and the explosion of blog sites."

"For those of us interested in politics, it was an endlessly fascinating process already, and it's still got some twists and turns between now and November," Clinton said.

The former president did say early in his remarks that the purpose of a party convention is to "introduce the candidate in a new and different and hopefully more positive way... [to] unify the party and [aid in] defining the battle" between the two parties.

The unifying-the-party aspect is what has many Democrats concerned about Clinton's Wednesday night remarks.

Clinton has been a media magnet throughout the year as his remarks have caused heartache and headaches to former and current supporters.

From when he called Obama's candidacy "a fairytale" to when he compared the Illinois senator's win in South Carolina to that of Rev. Jesse Jackson's, many Clinton loyalists, detractors and analysts feel that Clinton did irreparable damage to both his wife's candidacy and his legacy as president.

Now in a convention that continues to be racked with stories and questions about how unified the Democratic Party truly is, Clinton's appearance Wednesday — and his tendency to go off the teleprompter — has some Democrats very nervous.

Former Clinton aide and Democratic strategist Paul Begala, however, told The Hill that the former president is solidly behind Obama's candidacy.

"He's totally for Barack," Begala said Tuesday. "He's totally for Barack."