WASHINGTON — The thaw in the resentful relationship between the most powerful woman in the Democratic Party and her younger male rival began at the party’s convention this summer, when Senator Hillary Rodham Clinton gave such a passionate speech supporting Senator Barack Obama that his top aides leapt out of their chairs backstage to give her a standing ovation as she swept past.
Mr. Obama, who was in the first steps of what would become a strategic courtship, called afterward to thank her. By then, close aides to Mrs. Clinton said, she had come to respect the campaign Mr. Obama had run against her. At the least, she knew he understood like no one else the brutal strains of their epic primary battle.
By this past Thursday, when Mr. Obama reassured Mrs. Clinton that as secretary of state she would have direct access to him and could select her own staff, the wooing was complete.
“She feels like she’s been treated very well in the way she’s been asked,” said a close associate of Mrs. Clinton, who like others interviewed asked for anonymity because the nomination will not be formally announced until after Thanksgiving.
Few are predicting that this new relationship born of mutual respect and self-interest will grow into a tight bond between the new president and the woman who will be the public face of his foreign policy, though some say it is not impossible. They argue that a close friendship between the two powerful officials is useful but not essential, and is not a predictor of the success of the nation’s chief diplomat.
While James A. Baker III was extraordinarily close to the first President George Bush and is widely considered one of the most successful recent secretaries of state, Dean Acheson was not a friend of Harry S. Truman and Henry A. Kissinger did not particularly like Richard M. Nixon.
“Two of the nation’s greatest secretaries of state in the modern period, Dean Acheson and Henry Kissinger, were not personally close but were intellectually bonded to their presidents,” said Walter Isaacson, the author of a biography of Mr. Kissinger and the co-author, with Evan Thomas, of “The Wise Men,” a book about America’s postwar foreign policy establishment. “I think that Obama and Clinton could form a perfect partnership based on respect for each other’s view of the world.”
Colin L. Powell, who was President Bush’s first-term celebrity secretary of state, would appear to be a cautionary tale for Mrs. Clinton since his relationship with the president was strained, and he left office an unhappy man. But Mr. Bush’s second-term secretary of state, Condoleezza Rice, is generally not viewed as having the success her unusually tight bond with the president might have engendered.
In the Obama-Clinton relationship, advisers say, the relatively smooth nature of their talks about the secretary of state job indicate that both, for now, have a working chemistry. The advisers say that Mr. Obama was clearly interested in bringing a rival under his wing, and that he also recognized that Mrs. Clinton had far more discipline and focus than her husband.
At the same time, Mr. Obama’s advisers said, he had the self-confidence to name a global brand as his emissary to the world. He recognizes, they said, that after Jan. 20, he will have to build the kind of relationship that ensures that foreign leaders know that when Mrs. Clinton speaks, she is speaking directly for him.
“It helps to have a relationship that Bush had with Baker, that’s no doubt true,” said Martin Indyk, a former American ambassador to Israel, who was a supporter of Mrs. Clinton in the primary battles. “But if they are seen as working together effectively, I think that can be easily overcome. I don’t think he would have decided to appoint her if he didn’t want her to be effective.”
One close adviser to Mr. Obama said the president-elect also saw that Mrs. Clinton’s political skills would serve her well in the job, as happened with Mr. Baker and Mr. Kissinger. “They understood that statecraft is politics by another name,” the adviser said.
Mr. Obama and Mrs. Clinton first spoke after their primary fight on a flight in June to Unity, N.H., their first stage-managed appearance after he won the nomination. As they settled into their seats on his plane, the conversation, according to people on both sides, was far less awkward than they had feared. Over the passing weeks, the relationship gradually improved.
“They got past this long before their supporters and the party activists did,” said one Democrat who is close to both Mr. Obama and Mrs. Clinton.
After Mrs. Clinton’s speech in support of Mr. Obama at the Democratic convention, she crisscrossed the country tirelessly to campaign for him — so much so that he told aides he was impressed by the sheer number of events she was doing on his behalf.
Mrs. Clinton, it should be said, was herself diligent in advertising how hard she was working for the man who defeated her. When announcing her appearances, her press office included tallies of how many events she had held for Mr. Obama, and in how many states. At some rallies, organizers would distribute “Hillary Sent Me” buttons, as if Mrs. Clinton was being magnanimous by “sending” her followers to vote for Mr. Obama.
But Mr. Obama began calling Mrs. Clinton after some of the events — he dialed directly from his cellphone to hers one day in Michigan and another day in Florida — to check in and thank her for helping. By then, their intense primary fights over policy, which both sides now insist was more about heat than substance, had long receded.
“The reality at the end of the day was, whether it was Iran or health care or some of these other issues, we were always fighting big battles over small differences,” said a senior aide to Mr. Obama, adding that “in a campaign, conflict is what you go to.”
Substantively, the two were at odds over the Iraq war — Mrs. Clinton voted to authorize it and Mr. Obama said he would have opposed it had he been in the Senate then — and to a lesser extent over negotiations with Iran. But although Mrs. Clinton criticized Mr. Obama for being willing to sit down and talk to dictators, he has said he would have a lower-level envoy do preparatory work for a meeting with Iran’s leaders first. Mrs. Clinton has said she favors robust diplomacy with Iran and lower-level contacts as well.
In the weeks just before the election, the relationship between Mr. Obama and Mrs. Clinton further mellowed, even as she found herself in a startling role reversal with her younger rival. As a celebrity senator and powerhouse on Capitol Hill, she had helped Mr. Obama in his Senate race and offered advice when he first came to Washington; now she was the workhorse for a political phenomenon.
Since the election, Mrs. Clinton has talked to Mr. Obama only a handful of times, even as two close advisers to Mr. Obama who held top positions in the Clinton administration — Rahm Emanuel and John D. Podesta — have served as key negotiators between her and the president-elect on the secretary of state position.
But Mrs. Clinton has talked several times to Michelle Obama about raising a family in the White House and private schools in Washington. On Friday, Mrs. Obama said the two Obama girls, Malia and Sasha, would attend the Sidwell Friends School, just as Chelsea Clinton did.
Jeff Zeleny contributed reporting from Chicago, and Mark Leibovich from Washington.