DENVER (Reuters) - Republican Mitt Romney came across as aggressive and polished, while Democrat Barack Obama appeared laid back and unassertive in a presidential debate on Wednesday that showcased their differences in style as much as substance.
Known for his eloquence, the Democratic president stammered and paused during many answers, looking down at his podium when he was not speaking.
Romney, a former private equity executive, spoke in lists and was more concise than Obama, who has practiced unsuccessfully at tamping down his professorial style.
"With regard to body language, Mitt Romney was the winner," said Janine Driver, an expert on body language and author of "You Can't Lie to Me."
Driver said Obama kept his head tilted to the side rather than upward, projecting less confidence. Romney kept his head "on straight" and his eyes focused either on the president or the moderator, an improvement over his tendency to shift his eyes in different directions, she said.
"If you were from another country and you watched this based on body language, people would think that Mitt Romney was already the president," she said.
Stage movements can leave powerful lasting impressions on American viewers.
Democratic Vice President Al Gore's frequent sighs in a 2000 debate with Republican George W. Bush fared poorly with voters, and President George H.W. Bush's quick glance at his watch during a 1992 debate made him seem impatient.
Neither Obama nor Romney committed a debate-defining body language gaffe in the first of three presidential debates before the November 6 election.
Despite their differences, the two men shared a mostly polite stage rapport. They shook hands warmly at the beginning and end of the encounter, each using a free arm to touch the other man's shoulder.
While Obama in 2008 referred to opponent Senator John McCain by his first name during some debates, he and Romney, a former Massachusetts governor, addressed each other using titles throughout the night.
But Romney's more assertive style conveyed confidence and authority, while Obama seemed detached and less engaged.
"Obama remained overly controlled and contained in both his face and in his body - whereas Romney let his energy pour out," said Peggy Hackney, a body language expert at the University of California Berkeley and New York University.
"Romney was much more fully invested in his gestures and his flow spread throughout his body more often, making him seem more authentic and less studied or worried."
The campaigns had their own ratings for how their candidates performed stylistically. An Obama aide said Romney appeared testy and defensive, while a Romney aide said the president "struggled."
With Obama ahead in the polls before the debate, only a shift in the numbers will show whether his and Romney's body language had more than just a visual impact.
"I think Romney helped himself by looking engaged and energized, but overall this does not seem like the kind of debate that will move the electorate in dramatic fashion," said Princeton University history professor Julian Zelizer.
Editing by Marilyn W. Thompson and Peter Cooney