Clinton will publicly back Obama on Saturday and pledge to work for party unity in the general-election race against Republican John McCain.

"Senator Clinton will be hosting an event in Washington, DC to thank her supporters and express her support for Senator Obama and party unity," a campaign statement said.

The event was originally planned for Friday but the day was switched to allow more supporters to attend. The New York senator has not decided whether to officially close the campaign or suspend it, allowing her to keep control of her delegates to the nominating convention, aides said.

Clinton spent much of the day talking to supporters, many of whom urged her to halt her bid now that Obama has clinched the nomination. Obama attended two fundraising events in New York City on Wednesday night and acknowledged her decision.

"Your junior senator from New York engaged in an extraordinary campaign," he told attendees at one fundraiser. "Now that the interfamily squabble is done, all of us can focus on what needs to be done in November."

Obama, the first black candidate to lead a major U.S. party into a White House race, announced a three-member team to head his search for a running mate as he began the task of unifying the party the day after clinching the nomination.

McCain proposed that Obama join him for a series of joint summer town-hall meetings across the country. Obama's campaign manager called the idea "appealing" but proposed format changes and made no immediate commitment.

Caroline Kennedy, daughter of the late President John Kennedy, will vet prospective Obama running mates along with former Deputy Attorney General Eric Holder and Jim Johnson, former chief executive of the mortgage lender Fannie Mae, who performed the same task for Democrats John Kerry in 2004 and Walter Mondale in 1984.

Near the top of their agenda will be questions about a possible teaming with Clinton, who has indicated interest in the job after her presidential bid fell short.

"We're going to be having a conversation in coming weeks," Obama told reporters when asked about the former first lady. He said he was confident the party would be unified to win the general election.

After news of Clinton's decision broke, Obama adviser Linda Douglass told reporters she ran a great race.

"Her supporters have every reason to gather and celebrate that and we're confident the party will be united with her help," she said.

Obama returned to Capitol Hill to a hero's welcome from Democrats who swarmed to shake his hand and hug him.

"Our focus now is on victory in November and on giving Barack Obama every ounce of our support," eight previously uncommitted Democratic senators said in a statement.

OBAMA AIMS AT MCCAIN

Obama took aim at McCain for his staunch support of the Iraq war during a speech to a pro-Israel lobbying group in Washington, saying the Arizona senator "refuses to understand or acknowledge the failure of the policy that he would continue."

"He criticizes my willingness to use strong diplomacy, but offers only an alternate reality -- one where the war in Iraq has somehow put Iran on its heels," he said. "Senator McCain offers a false choice: stay the course in Iraq, or cede the region to Iran."

In the same speech, Obama tried to smooth relations with Clinton after their long and sometimes bitter nominating fight, calling her an "extraordinary candidate and extraordinary public servant."

Clinton, in a later speech to the same group, complimented Obama and said she knew he would be a friend to Israel.

Clinton's supporters turned up the pressure for the New York senator to be named as Obama's vice presidential candidate. Robert Johnson, founder of Black Entertainment Television, said he wrote to the Congressional Black Caucus urging members to push Obama to choose Clinton.

Obama's campaign said the search was just beginning.

"Senator Obama is pleased to have three talented and dedicated individuals managing this rigorous process," spokesman Bill Burton said. "He will work closely with them in the coming weeks but ultimately this will be his decision and his alone."

The victory by Obama, son of a black Kenyan father and white mother from Kansas, marked a milestone in U.S. history. It came 45 years after the height of the civil rights movement and followed one of the closest and longest nomination fights in recent U.S. political history.

Obama's achievement drew praise from Republican Secretary of State Condoleezza Rice, the highest-ranking black in President George W. Bush's Cabinet.

"It's a country that has overcome many, many, now years, decades of, actually a couple of centuries, of trying to make good on its principles," Rice said.