By Jeff Mason

WASHINGTON (Reuters) - Barack Obama filled stadiums on a regular basis during his 2008 presidential campaign but has steered clear of them for his final White House bid.

So the decision to deliver his nomination-acceptance speech at the Democratic National Convention next Thursday in a football stadium with nearly 74,000 seats has raised a basic, if uncomfortable, question: Can he fill the venue?

The president's team is working hard to do just that by distributing free tickets at campaign offices in Charlotte, North Carolina, where the convention is being held, and throughout the state.

Residents of neighboring states such as Virginia and South Carolina will travel to Charlotte as well to fill up spots at the Bank of America stadium, the home of the National Football League's Carolina Panthers.

"We don't think we're going to have turnout problems," one Obama campaign official said. "It's clearly a great opportunity for us to get more people involved."

The convention opens Tuesday at the Time Warner Cable Arena and on Thursday will shift to the football stadium for what will be Obama's biggest campaign event so far this year.

With millions watching on television, a full stadium would give the party the inclusive, populist feel it tried to achieve four years ago at its convention in Denver. There, organizers wanted to accommodate more people, so Obama's acceptance speech was moved to the Denver Broncos' football stadium, which ended up full.

Obama drew huge crowds at his campaign events in 2008, providing him a boost of momentum in both the Democratic primary race to best then-Senator Hillary Clinton and, later, to beat Republican John McCain in the general election.

Tens of thousands of people regularly filled arenas to see the candidate of hope and change that year, and some 200,000 people showed up to hear him during a foreign trip to Berlin.

Not anymore. Obama's re-election effort has lacked the large numbers and big venues that were a constant four years ago. During a bus tour of Iowa recently he spoke to groups that ranged from a few hundred to a few thousand.

"He was a big celebrity in 2008. Now he's pretty much just another politician," said Charlie Black, a Republican strategist who worked on McCain's presidential campaign.

Black said the radio ads and personnel needed to entice people to the Charlotte stadium would be costly.

"They're going to spend an incredible amount of resources to fill up that stadium," he said.

LONG LINES

Obama's first major rally in May took place at an 18,300-person arena in Ohio. Entire balconies of empty seats stood out, drawing notice in press reports. The campaign said 14,000 people attended, and noted that Romney's largest event in Ohio at the time had drawn just 500 people.

Empty seats in Charlotte would draw unwelcome attention, too. Campaign and convention officials were reluctant to outline plans for filling the stadium, including how many tickets had been passed out, but so far the numbers look promising for them.

Tens of thousands of people lined up at offices in North Carolina last weekend to get the credentials needed to secure a seat, Obama officials said.

Tickets in neighboring states also are going fast. A spokeswoman for the Democratic Party in South Carolina said the 6,000 passes allotted to her state were gone.

"I support the president. I want to hear the speech," said attorney Eli Poliakoff, 34, who stood in line with others at an Obama campaign office in Charleston.

"You look at this crowd and you have different backgrounds and ages and races and religions and all that's good for democracy."

The campaign also lured participants with a program that rewards people with seats in return for nine hours of volunteer time. Called the 9-3-1 program, more than 6,000 people signed up to give nine hours of work over three shifts in exchange for one spot in the stadium.

Another 6,000 delegates at the convention itself will have seats for Obama's speech, filling out the stadium with others from across the state and the country.

"That's the same thing that we did in Denver. You know, we were busing people from all over the state to get there and that's a good thing," said one Democratic official.

"It's a huge undertaking, there's no doubt about it. But we like the challenge."

Once they make it to the stadium on September 6, the crowd, large or small, will have a while to wait. Convention planners recommend arriving early -- parking lots open at 11 a.m. (1500 GMT) -- and bringing sunscreen. Officials have not announced what time Obama's speech will begin but it is likely to be in the late evening during television's prime viewing time.

(@jeffmason1; Additional reporting by Harriet McLeod in Charleston; Editing by Alistair Bell and Bill Trott)