Voices in the US are growing louder asking the question: Is Barack Obama all style and little substance?

The freshman Illinois senator began his campaign facing the perception that he lacks the experience to be president, especially compared to rivals with decades of work on foreign and domestic policy. So far, he has done little to challenge it. He has delivered no policy speeches and provided few details about how he would lead the country.

Instead, he has focused on motivating his impressive following with a call for unity and change in Washington. But along with the attention comes a hunger to hear more about what he is about. “The Obama campaign has been smart about recognising that voters don’t want to be lost in the valley of policy only,” said Democratic consultant Jenny Backus. “But it’s a gap that’s going to have to be filled as he goes on.”

Obama has a lot of time to fill in the blanks between now and Election Day in November 2008, and certainly many other candidates are short on details this early in the race. But they do not have such a barrier to prove they are qualified to be president.

At a union forum yesterday, Obama sought to answer the questions, arguing that he has experience as a state legislator, community organiser and constitutional law professor. He also cited his work in the Senate on nuclear proliferation. “I am confident in my ability to lead,” Obama told the crowd.

The differences among the Democratic candidates were on display on Saturday in Las Vegas, where the contenders answered questions about health care, expected to be a key issue in the campaign. More than 45 million Americans do not have health care.

Former North Carolina Sen. John Edwards, the only other candidate to serve less time in elective office than Obama, described in detail his health care plan to provide insurance for all Americans. New York Sen. Hillary Clinton does not have a written plan yet, but no one questions her expertise, since she was the chief proponent of the issue during her husband’s presidency.

Daniel Romo, 45, a clerk at Kaiser Permanente in Los Angeles and a member of the Service Employees International Union that sponsored the forum, left with Clinton and Edwards as his top choices. Obama did not impress him. “I believe that he needed to know a little more about health care issues and he was just unprepared,” Romo said.

Obama was pressed by a union member in the audience who said she went to his website to learn more about his health care vision, but did not find much beyond his commitment to reduce HIV/AIDS and lead poisoning.

“Keep in mind that our campaign now is I think a little over eight weeks old,” Obama said. He promised that a detailed plan would show up in the next couple of months, after he has a chance to talk to more people involved in the system to get their input.

If Obama were running in a different time, he might get more of a break for lacking specifics. Primary votes were already being cast in the 1984 Democratic primary when Sen. Walter Mondale famously ridiculed opponent Sen. Gary Hart by asking, “Where’s the beef?”

Four years ago, no candidate for president had a health-care plan this early in the game. — Associated Press