Multiple reports say Hillary Clinton will concede or suspend her campaign at the end of the week, in a step toward uniting the Democratic Party under the leadership of presumptive nominee Barack Obama.

ABC News reports that Clinton will concede in a speech to supporters in Washington, D.C., while The Associated Press says she will end her campaign but possibly retain her delegates.

Clinton's communications director Howard Wolfson released a statement saying, "Senator Clinton will be hosting an event in Washington, D.C., to thank her supporters and express her support for Senator Obama and party unity. This event will be held on Saturday to accommodate more of Senator Clinton's supporters who want to attend."

The event had earlier been scheduled for Friday, and Wolfson did not confirm whether she would officially concede the race to Obama.

Earlier in the day, Obama quickly shifted gears into general election mode by setting up a vice-presidential search team.

Obama named Caroline Kennedy and two party insiders -- Jim Johnson and Eric Holder -- to the team that will begin vetting the possible second name on the presidential ticket.

Kennedy, daughter of the late president John F. Kennedy, is a beloved figure in the Democratic Party -- and had helped secure Sen. Ted Kennedy's backing for Obama early in the primary race.

Obama also told reporters Wednesday that he had spoken with Clinton and expressed optimism that the party's unity could be renewed.

The Illinois senator spoke with Clinton a day after he claimed the nomination and the New York senator had refused to concede -- an act some saw as a negotiating ploy, possibly to gain the vice-presidential nomination.

"I just spoke to her today, and we're going to be having a conversation in coming weeks. And I'm very confident how unified the Democratic Party's going to be to win in November," Obama told reporters as he left the Senate in Washington.

Asked if Clinton indicated she planned to concede, Obama replied, "It wasn't a detailed conversation. As I said, I'm very confident of how we're going to be able to bring the party together."

The two crossed paths at the American Israel Public Affairs Committee (AIPAC) meeting. Some analysts have suggested that Obama faces some questions from the Jewish community in the U.S. because of his Middle East policies. Clinton told AIPAC members that Obama would be "a good friend to Israel."

Obama also exchanged shots with Sen. John McCain, the presumptive Republican nominee.

"I think he has exercised very bad judgment on national security issues and others," McCain said in a morning television interview.

Obama fired back.

"Keeping all of our troops tied down indefinitely in Iraq is not the way to weaken Iran, it is precisely what strengthened it," Obama said in his AIPAC speech, in which he also described the security of the Jewish state as sacrosanct.

Clinton as VP?

Next to figuring out how to defeat McCain, deciding how to handle Clinton may be Obama's most vexing political problem.

On Tuesday afternoon, Clinton said she would be "open" to the idea of being Obama's running mate. Clinton reportedly made the remarks during an afternoon conference call among members of the Democratic Party's New York congressional delegation.

"I think a lot of her supporters would like to see her on the ticket," said her campaign chairman, Terry McAuliffe said.

"There is no deal in the works," said Obama's spokesman, Robert Gibbs.

The two drew support from distinctly different demographic groups. Obama had the support of young voters, black voters and the educated. Clinton's support came from women, rural white working-class voters, Latinos and the uneducated.

Former President Jimmy Carter told a British newspaper that if Obama picks Clinton "it would be the worst mistake that could be made."

"What he needs more than a southerner is a person who can compensate for his obvious potential defects, his youthfulness and his lack of long experience in military and international affairs," Carter told the Guardian.

Presidential historian Allan J. Lichtman said there are advantages and disadvantages to the possible pairing.

"There is some chance. There's a lot to commend that ticket," he told Canada AM.

"They have generated enormous momentum and enormous new Democratic registrants in this campaign - and they could keep the momentum going. And think of the message to young people -- no matter what your race, no matter what your gender, you can rise to the top in American politics."

The downside to an Obama/Clinton ticket, he said, is baggage from Clinton's term as first lady during her husband Bill Clinton's term in office, and the effect of having a consummate insider like her as vice-president would have on Obama's message of change.

While Clinton clearly has a strong support base, she is a polarizing figure in American politics. Some polls have found 40 per cent of respondents saying they wouldn't vote for her under any circumstance.

With files from The Associated Press