Senator Barack Obama gave his speech on race yesterday in Philadelphia. His audience was the whole country, if not the world. But it’s worth considering what effect the speech might have on his immediate audience in Pennsylvania, which holds the nation’s next primary on April 22.

The Obama campaign often says it needs to “introduce” Mr. Obama to Pennsylvania, which is another way of saying that voters there don’t know him. The campaign clearly made a decision that the benefits of introducing him with a high-profile speech assessing the nuances of race in 21st-century America were worth the potential risks.

Those benefits would be most evident among those already supporting him: black voters in Philadelphia and part of Pittsburgh; affluent white liberals, most of them in Center City Philadelphia and the suburbs; Independents and possibly moderate Republicans; and students and other young people, particularly those against the war in Iraq. These groups form the kind of coalition that Mr. Obama has built in other states and that are likely to form his base in Pennsylvania.

“He did take a risk, but he saw this as something bigger than his candidacy, bigger than this election,” said Camille Charles, an Obama supporter who is an associate professor of sociology at the University of Pennsylvania.