Clinton to formally endorse Obama

By Scott Helman, Globe Staff

Senator Hillary Clinton plans to formally endorse Barack Obama on Saturday at a Washington event with her supporters and call on Democrats to unite behind their presumptive presidential nominee.

But her initial reluctance to back Obama and the continuing mystery over how exactly she will end her historic campaign had party faithful asking today: What is she waiting for, and what does she want?

Clinton has thanked her campaign staff for their work and discussed potential exit strategies with top advisers and supporters, who say she is resigned to not being the nominee. She has praised Obama for running a strong race. And she has vouched for his support for Israel before a leading pro-Israel lobbying group.

But the New York senator had yet to publicly acknowledge that Obama beat her for the nomination, leaving some of his supporters — and even some of hers — perplexed and disappointed.

Clinton could have been ‘‘far more generous’’ to Obama in conceding victory in her speech Tuesday night, US Representative Charles Rangel of New York, one of Clinton’s strongest backers, said on MSNBC today.

Other Clinton supporters said she recognized that the race was over, but simply needed breathing room before making a definitive statement, which apparently will come Saturday. ‘‘Senator Clinton will be hosting an event in Washington, DC to thank her supporters and express her support for Senator Obama and party unity,’’ her campaign said in a statement issued tonight. ‘‘This event will be held on Saturday to accommodate more of Senator Clinton's supporters who want to attend.’’

‘‘She’s absolutely committed to making sure the Democrats win in November,’’ said US Representative James McGovern of Worcester, a member of Clinton’s inner circle. ‘‘She will do nothing that undermines that.’’

McGovern cited the intensity of Clinton’s support, particularly among women, and said that she had to think through the most effective way of getting her loyalists behind Obama in the fall. ‘‘Going out [Tuesday] night and simply saying it was over would not have resulted in the unity that we all wanted,’’ McGovern said.

Despite the uncertainty, Obama’s campaign today moved ahead with its general election campaign against presumptive GOP nominee John McCain, making plans to tour Virginia, North Carolina, and other potential battleground states, expressing a willingness to hold joint campaign events with the Arizona senator, and announcing a committee to vet possible vice presidential candidates. The team will be led by Caroline Kennedy Schlossberg, the daughter of John F. Kennedy; former Clinton administration official Eric Holder; and Jim Johnson, a former CEO of Fannie Mae who has performed a similar task for past Democratic nominees.

To many Clinton supporters, Obama’s best choice is obvious: Clinton, and, with her at least tacit approval, some of her most ardent backers have been ratcheting up pressure on Obama’s team to put her on the ticket — even though it is not entirely clear how eager either of them is for that outcome.

Long-time Clinton adviser Lanny Davis announced plans for a website and petition drive to pressure Obama into picking Clinton. Bob Johnson, the founder of Black Entertainment Television, wrote a letter to the Congressional Black Caucus asking the group to urge Obama to do the same. Clinton, Johnson said, knew of his efforts.

‘‘I have been in touch with her all the way in my thinking about how we can move this country in a unified way, and she’s prepared to be a part of that unity,’’ he told CNN today.

‘‘We have the best chance of winning with Senator Obama at the top of the ticket, Senator Clinton as his vice president,’’ Johnson added.

But some Obama supporters are adamant about her not being on the ticket.

‘‘We don’t want her as vice president,’’ Judith Shilling, a 68-year-old retiree from the University of Minnesota, offered without prompting as she waited Tuesday to get into Obama’s victory rally in St. Paul.

Former president Jimmy Carter, who endorsed Obama Tuesday, told The Guardian, a British newspaper, that selecting Clinton would be ‘‘the worst mistake that could be made,’’ pointing to polls showing that many voters hold unfavorable opinions of her.

Some analysts say that the public appeals by Clinton’s associates could box Obama in and risk angering her millions of supporters if he chooses someone else.

‘‘The more they talk about it, the more reporting there is that she’s actively interested in joining the ticket, the more it’s a problem if and when he rejects her,’’ said Stuart Rothenberg, who publishes the nonpartisan Rothenberg Political Report. ‘‘That would look like a real snub.’’

Rothenberg noted, however, that there have been instances where political calculation, more than anything else, led to fierce primary rivals ending up side-by-side on a ticket. In 1960, Kennedy picked Lyndon Johnson, then a powerful leader in the Senate; in 1980, Ronald Reagan selected George H.W. Bush after Bush famously dismissed what he called Reagan’s ‘‘voodoo economics.’’