Barack Obama effectively clinched the Democratic presidential nomination Tuesday after a grueling marathon, based on an Associated Press tally of convention delegates, becoming the first black candidate ever to lead his party into a fall campaign for the White House. Campaigning on an insistent call for change, Obama outlasted former first lady Hillary Rodham Clinton in a historic race that sparked record turnout in primary after primary, yet exposed deep racial and gender divisions within the party. The tally was based on public declarations from delegates as well as from another 15 who have confirmed their intentions to the AP. It also included 11 delegates Obama was guaranteed as long as he gained 30 percent of the vote in South Dakota and Montana later in the day. It takes 2,118 delegates to clinch the nomination. The 46-year-old first-term senator will face John McCain in the fall campaign to become the 44th president. The Arizona senator campaigned in Memphis during the day, and had no immediate reaction to Obama's victory.Clinton stood ready to concede that her rival had amassed the delegates needed to triumph, according to officials in her campaign. They stressed that the New York senator did not intend to suspend or end her candidacy in a speech Tuesday night in New York. They spoke on condition of anonymity because they had not been authorized to divulge her plans.