From the 2004 Democratic convention speech that launched him onto the national stage to his acceptance of his party's nomination four years later, Barack Obama's public speaking skills have been considered one of his strongest assets.

But while the president's ability is admired -- and at least one Web site promises to teach it to you -- Obama also is mocked by critics who say he's only comfortable with teleprompters.

One Web site has compiled clips of him stumbling verbally without them. For example: "And if they just gave him treatment early, and, uh, they got some treatment," he misspoke at a campaign stop. "And a breathalyzer..uh a inhalator."

His predecessor, President Bush, used a teleprompter less often and paid the price for his verbal gaffes.

"One has a stronger hand when there's more people playing your same cards," Bush said in one of many misstatements that are a part of his legacy.

But it can be argued that Bush's best moments were unscripted. After the Sept. 11 terrorist attacks, Bush rallied the nation with his words of conviction and courage.

"And the people who knocked these buildings down will hear all of us soon," he said then in New York.

Experts say every president since Franklin D. Roosevelt has had a different style of communicating through technology with the American people, and in challenging times the impossible often is asked of them.

"The bully pulpit is critical but it also doesn't change the reality," said Larry Sabato, the director of the Center for Politics at the University of Virginia. "The reality is we're going to be in duck soup for a long time to come."

Bill Clinton experienced a nightmare during his 1994 State of the Union address.

"I'm not at all sure what speech is in the teleprompter tonight," he said then to laughter, "but I hope we can talk about the state of the Union."

Clinton ad-libbed until the right speech was found.

Obama's inaugural address, delivered with a teleprompter, was not considered his most moving speech. But two weeks later, without a prompter, he made an impassioned push for his stimulus plan at a retreat held by congressional Democrats.

"These are families you know and you care about," he said. "I believe that it is important for us to set aside some of the gamesmanship in this town and get something done.

Sabato says using a prompter is mostly a matter of style, but its most important role is to keep a person on message. He says few presidents can go off message without getting into trouble.