(wapo) With a split decision in the final two primaries and a flurry of superdelegate endorsements, Sen. Barack Obama sealed the Democratic presidential nomination last night after a grueling and history-making campaign against Sen. Hillary Rodham Clinton that will make him the first African American to head a major-party ticket. Before a chanting and cheering audience in St. Paul, Minn., the first-term senator from Illinois savored what once seemed an unlikely outcome to the Democratic race with a nod to the marathon that was ending and to what will be another hard-fought battle, against Sen. John McCain, the presumptive Republican nominee. "Tonight we mark the end of one historic journey with the beginning of another -- a journey that will bring a new and better day to America," he said, as the emotion of the moment showed on his face. "Because of you, tonight I can stand before you and say that I will be the Democratic nominee for president of the United States of America." Obama's success marked a major milestone for the nation -- a sign of the racial progress that has taken place during the span of the senator's lifetime. But the nomination battle also revealed a racial schism within the Democratic Party, and potential resistance to a black candidate in some parts of the country that will play out in the general-election campaign.