By JODI KANTOR

From his days leading The Harvard Law Review to his United States presidential campaign, Barack Obama has always run meetings by a particular set of rules.
Everyone contributes; silent lurkers will be interrogated.
(He wants to “suck the room of every idea,” said Valerie Jarrett, a close adviser.) Mention a theory and Mr. Obama asks how it translates on the ground. He orchestrates debate, playing participants off each other - and then highlights their areas of agreement. He constantly restates others’ contributions in his own invariably more eloquent words. But when the session ends, his view can remain a mystery .
Those meetings, along with the career they span, provide hints about what sort of president Mr. Obama might be if elected. They suggest a cool deliberator, a fluent communicator, a professor with a hunger for academic expertise but little interest in abstraction. He may be uncomfortable making decisions quickly or abandoning a careful plan. A President Obama would prize consensus, except when he would disregard it. And his lifelong penchant for control would likely translate into a disciplined White House.
Winning the presidency on Tuesday, as polls predict he will, would be the latest in a lifetime of dramatic, self-induced transformations: from a child reared in Indonesia and Hawaii to a member of Chicago’s African-American community; from an atheist to a Christian; from a wonkish academic to the smoothest of politicians; and now, just possibly, from an upstart who eight years ago was crushed in a Congressional race to the first black commander in chief of the United States.
Turning deficits into assets could wellbe called the motto of his rise. He transformed a fatherless childhood into a stirring coming-of-age tale. He used a glamourless state senator’s post as the foundation of his political career. He mobilized young people into an energetic army . And even though his exotic name, Barack Hussein Obama, has spurred false rumors and insinuations about his background and beliefs, he has made it a symbol of his singularity and of America’s possibility.
But if he wins the right to occupy the Oval Office, Mr. Obama would have a new set of deficits. Just 47 years old and only four years into a national political career, he has never run anything larger than his campaign. His promises are as vast as his resume is short, and some of his pledges are competing ones: progressive rule and centrist redblue fusion; wholesale transformation and pragmatism.
Mr. Obama has prized order. Even at Occidental College in Los Angeles, during what he has called his dissolute phase, students remember him as a model of moderation . “He was not even close to being a party animal,” said Vinai Thummalapally, a friend from those years.
When it comes to making decisions, Mr. Obama’s impulse for control translates into a kind of deliberative restraint. He resists making quick judgments or responding to day-to-day fluctuations, aides say. Instead he follows a familiar set of steps: Perform copious research. Solicit expertise. Project all likely scenarios. Devise a plan. Anticipate objections. Adjust the plan, and once it’s in place, stick with it.
Mr. Obama does not always react swiftly to unexpected shifts. When Russia blitzed into neighboring Georgia, he took several days to settle on a position. After Senator John McCain’s surprise selection of Governor Sarah Palin as his running mate, the Obama campaign seemed to struggle to respond.
The only time Mr. Obama slips from “his normal cool self,” said Marty Nesbitt, a close friend, is “when something surprises him.”
His critics point to his “present” votes in the Illinois Legislature, in which he did not choose sides, avoiding difficult matters like trying juveniles as adults. At least 36 times (out of thousands of votes) Mr. Obama was the only senator to vote “present,” or one of just a few.
But defenders say Mr. Obama’s reticence is as intellectual as it is tactical. He is suspicious of generalizations.
Most of the time, Mr. Obama speaks lightly of the historic nature of his candidacy . But a few times during the campaign he allowed voters to see just how heavily America’s divided past sits on his slender shoulders. That weight seems like part of the answer to a central Obama mystery: where all of that burning ambition comes from, what possesses him to push so hard and so fast.
Nearly two decades ago at Harvard University, Mr. Obama had his first taste of a barrier-smashing presidential victory . Gordon Whitman, one of the classmates who decided that long-ago election for president of the Harvard Law Review, recalled: “We all understood there was a chance to make history.”