Chicago is not Obama’s home town, but it’s where he chose to forge his identity. Several weeks ago, he moved many of the Democratic National Committee’s operations from Washington to Chicago, making the city the unofficial capital of the Democratic Party; his campaign headquarters are in an office building in the Loop, Chicago’s downtown business district. But Chicago, with its reputation as a center of vicious and corrupt politics, may also be the place that Obama needs to leave behind.

But there has been little humor about Mr. Obama: about his age, his speaking ability, his intelligence, his family, his physique. And within a late-night landscape dominated by white hosts, white writers, and overwhelmingly white audiences, there has been almost none about his race.

“We’re doing jokes about people in his orbit, not really about him,” said Mike Sweeney, the head writer for Mr. O’Brien on “Late Night.” The jokes will come, representatives of the late-night shows said, when Mr. Obama does or says something that defines him — in comedy terms.

“We’re carrion birds,” said Jon Stewart, host of “The Daily Show” on the Comedy Central channel. “We’re sitting up there saying ‘Does he seem weak? Is he dehydrated yet? Let’s attack.’ ”

“As President, I will pursue a tough, smart and principled national security strategy — one that recognizes that we have interests beyond Baghdad, in Kandahar and Karachi, in Tokyo and London, in Beijing and Berlin,” he said. “I will focus this strategy on five goals essential to making America safer: ending the war in Iraq responsibly; finishing the fight against al Qaeda and the Taliban; securing all nuclear weapons and materials from terrorists and rogue states; achieving true energy security; and rebuilding our alliances to meet the challenges of the 21st century.”