Barack Obama effectively clinched the Democratic presidential nomination Tuesday, 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 divisions within the party.

The AP tally was based on public commitments from delegates as well as more than a dozen private commitments. It also included a minimum number of delegates Obama was guaranteed even if he lost the final two primaries in South Dakota and Montana later in the day.

The 46-year-old first-term senator will face Sen. John McCain of Arizona in the fall campaign to become the 44th president.

Clinton was ready to concede that her rival had amassed the delegates needed to triumph, according to officials in her campaign. These officials said 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.