Rejecting a last-ditch effort by former President Bill Clinton, Sen. Edward Kennedy firmly bestowed his blessing Monday on Barack Obama's presidential campaign.

"I'm proud to stand with him here today and offer my help, offer my voice, offer my energy, my commitment to make Barack Obama the next president of the United States," Kennedy boomed at high volume to an even louder crowd of mostly young supporters at the American University in Washington D.C.

"In Barack Obama, I see not just the audacity, but the possibility of hope for the America that is yet to be," Kennedy continued in an endorsement speech that also made heavy references to Kennedy's older brother, the late President John F. Kennedy.

Joining Obama and Kennedy onstage at the university were two other Kennedys -- Ted Kennedy's son, Patrick, who is a Rhode Island congressman, and his niece Caroline Kennedy, President Kennedy's daughter.

Robin Costello, a spokeswoman for Patrick Kennedy, told The Associated Press in a telephone interview that the senator and congressman probably will campaign around the country for Obama, although no concrete plans are set yet.

Together, the three make a formidable front of one of the nation's most famous political families. A liberal icon, Ted Kennedy's endorsement also brings with it a broad national fundraising and political network.

Sen. Kennedy has been critical of the Clinton campaign for injecting racial issues into the campaign, and in a thinly veiled blast that is usually saved for Republicans, he rejected the campaign's tactics.

"With Barack Obama, we will turn the page on the old politics of misrepresentation and distortion. ... We will close the book on the old politics of race against race, gender against gender, ethnic group against ethnic group, and straight against gay."

Referencing other Clinton campaign talking points -- on the question of experience and Obama's position on the war in Iraq -- Kennedy said the Illinois senator is "ready to be president on day one."

"We know the true record of Barack Obama. ... From the beginning, he opposed the war in Iraq ... and let no one deny that truth," he added.

The fact that Kennedy leaped into the race at all is a blow to Hillary Clinton's campaign, which had tried to convince Kennedy to stay neutral.

In response to the announcement, the Clinton campaign pulled out other Kennedy clansmen, including former Maryland Lt. Gov. Kathleen Kennedy Townsend, daughter of Robert F. Kennedy, to argue that Hillary Clinton also represents the Camelot legacy.

"I have known Hillary Clinton for over 25 years and have seen firsthand how she gets results. As a woman, leader, and person of deep convictions, I believe Hillary Clinton would make the best possible choice for president. She shares so many of the concerns of my father," Townsend said in a statement issued Sunday. "That is why my brother Bobby, my sister Kerry, and I are supporting Hillary Clinton."

Trying to downplay Obama's "get," the Clinton campaign also issued a statement saying regardless of which Kennedy supports which candidate, the election will be decided not by one family but by the voters themselves.

But the endorsement by Ted Kennedy and the daughter of John F. Kennedy is still a hit to Clinton, whose campaign staff had worked for weeks trying to encourage the senior senator to at least stay neutral in the primary battle that is pitting Obama's message of change against New York Sen. Hillary Clinton's message of experience.

The New York Times and Politico both detailed in Monday's editions how Bill Clinton personally appealed to Kennedy to refrain from making any endorsements before the end of the primary season, and how the Clinton campaign enrolled a number of friends to lobby Kennedy on Hillary Clinton's behalf.

Click here to read the full report in The New York Times.

Click here to read the full report in The Politico.

On Monday, Obama also won the endorsement of author Toni Morrison, who once wrote that Bill Clinton was the "first black president."

Morrison, whose acclaimed novels usually concentrate on the lives of black women, said she has admired Clinton for years because of her knowledge and mastery of politics, but then dismissed that experience in favor of Obama's vision.

She said her endorsement has little to do with Obama's race -- he is the son of a black father from Kenya and a white mother from Kansas -- but rather his personal gifts.

"In addition to keen intelligence, integrity and a rare authenticity, you exhibit something that has nothing to do with age, experience, race or gender and something I don't see in other candidates," Morrison wrote in a letter to the Illinois senator. "That something is a creative imagination which coupled with brilliance equals wisdom."

In 1998, Morrison wrote a column for the New Yorker magazine in which she wrote of Bill Clinton: "White skin notwithstanding, this is our first black president. Blacker than any actual black person who could ever be elected in our children's lifetime. After all, Clinton displays almost every trope of blackness: single-parent household, born poor, working-class, saxophone-playing, McDonald's-and-junk-food-loving boy from Arkansas."

The Associated Press contributed to this report.