Americans picking a president usually turn to people who have run states or armies. The biggest thing Barack Obama has ever run is his own presidential campaign.

The 47-year-old Illinois senator is asking voters to look beyond his thin resume and conclude that he has the wisdom and toughness to be president. The economy, terrorism, health care _ he hopes voters will trust him with all that and more.

That's a lot to ask for someone who just a few years ago was an obscure member of the Illinois Legislature.

"For many people, Obama's a wild card," said his former colleague, Democratic state Sen. Susan Garrett. "They like him. They want to give him a chance, but it's a big, big job. They need some reassurances that he's up to it."

Obama can remind voters of some concrete achievements, in Illinois and Washington. And running a marathon primary campaign that bested favored rival Hillary Rodham Clinton was no minor feat.

But the heart of Obama's sales pitch isn't what he's done. It's who he is.

He wants to be seen as someone who can empathize with people's problems, use his obvious brainpower to come up with solutions and then motivate everyone to work together. Any lack of experience he makes up for with sound judgment, according to this argument.

Exhibit A is Obama's early opposition to invading Iraq. He warned in 2002 that it would be a long, costly diversion from the war against al-Qaida in Afghanistan.

Exhibit B is his personal story. Black father and white mother, raised in Indonesia and Hawaii, a scholar who also spent years helping the poor in Chicago neighborhoods _ Obama is a walking billboard for bridging divides.

Those who know Obama best express confidence he can handle the Oval Office. They describe him as calm under pressure, someone who studies all angles, gathers advice from the best people, then makes a decision.

"He's not one who's going to shoot from the hip," said Democratic state Sen. Terry Link, a longtime Obama friend. "He's not one who's going to take gambles unnecessarily."

Presidential scholar Erwin Hargrove of Vanderbilt University concludes that character is the biggest part of a president's success or failure.

"I think the personal character is more important than the experience," he said.

Not so, says Samuel Skinner, White House chief of staff for the first President Bush. Temperament is important, but experience matters tremendously, too.

"It's a very complicated job with a lot of pieces that are constantly moving on you," Skinner said. "With experience comes confidence, and with confidence comes decisiveness."

Emergencies aren't the only challenges for a new president. Obama would also face the unfamiliar task of overseeing a massive bureaucracy.

Obama plans to address that by filling his Cabinet with Washington experts _ perhaps including Republicans. On Saturday he named Sen. Joe Biden of Delaware as his vice presidential running mate, balancing his ticket with a seasoned Washington veteran well-versed in foreign policy and defense issues.

Republican John McCain has been in Washington far longer than Obama, developing a reputation for expertise on the military and foreign affairs. But his executive experience is limited to 13 months as head of a Navy squadron of about 1,000 people and 75 planes.

Obama's opponents see voter doubts to be exploited.

Clinton ran the "3 a.m. phone call" ad that asked who voters wanted in the White House during an emergency. McCain compares Obama to fluffy celebrities Britney Spears and Paris Hilton.

When it comes to experience, Obama's supporters point out that he helped build consensus on difficult issues in Illinois such as death penalty reforms and stronger ethics laws. He worked with Republicans in the U.S. Senate to fight nuclear proliferation and government waste.

And he has run a groundbreaking presidential campaign. Obama energized new voters and turned the Internet into a fundraising tool in ways no one else has ever done. Even when his campaign struggled, Obama kept a lid on the leaks and finger-pointing that weaken many campaigns.

Skinner, now a Chicago lawyer, said voters can learn something from that.

"If the campaign is disorganized and the candidate is disorganized, that might be an indication they can't put a White House together," he said.

Obama reached the national stage thanks to his speaking abilities. Soaring and emotional to cool and analytical, they have been a big part of his success.

As president, that skill could help him rally people behind his policies. But critics still question his seasoning.

Republican state Sen. David Luechtefeld, a former Obama poker buddy who has been in public office 13 years compared with Obama's 11, said, "His experience is certainly not something you would look at and say 'This is who I want to be leader of the free world.'"


EDITOR'S NOTE _ Associated Press Springfield Correspondent Christopher Wills has covered Barack Obama since he began serving in the Illinois Senate in 1997.