WASHINGTON China's leader-in-waiting Xi Jinping won the kind of reception in the United States that suggests Washington sees his rise as a chance to narrow economic and political rifts.
Converting the warm mood music brought by Xi into substantively improved Sino-U.S. ties, however, will demand concessions that both sides are likely to resist.
Vice President Xi is virtually sure to succeed Hu Jintao as China's president in just over a year, and the mix of flattering attention and impatient demands that greeted Xi in the United States showed the Obama administration wants to make sure he enters the top job with a firm grasp of what Washington wants.
"China is no different from other countries in the sense that when you have the same leader hanging on, it's more difficult to change established policy, but China now has a situation where you can make adjustments in policy because of a pattern of regular turn-over," said J. Stapleton Roy, who was the U.S. ambassador in Beijing from 1991 to 1995.
"It does not necessarily make a big difference, but every time you change a leader, you have greater potential for change of policies," said Roy, who directs the Kissinger Institute on China and the United States.
President Barack Obama and Vice President Joe Biden appear to nurse some hopes that Xi's ascendance could bring greater Chinese accommodation. They spent plenty of time getting to know him, and he received a high-level reception at the Pentagon.
In turn, Xi (pronounced like "shee") put a folksy smile on China's usually grim-faced officialdom by returning to Muscatine, a town in Iowa he visited as a young cadre in 1985.
Xi also played on U.S. hopes for more trade and investment, a message he will also take to his final U.S. stop, Los Angeles, on Friday.
"From the U.S. point of view, a change in (Chinese) leaders is a natural opportunity to reset ties," said Robert Kuhn, an American biographer of Chinese leaders who has also advised them and has met Xi.
"Xi appears comfortable in his own skin and less worried about deviating from some script," said Kuhn.
But despite the shows of bonhomie and China's effusive media coverage, Xi's visit was punctuated by flashes of the tensions that weighed on ties during President Hu's time, and are likely to persist whoever succeeds Hu or wins the November U.S. presidential election.
Obama, Biden and senior members of the U.S. Congress plied Xi with demands that Beijing do more to balance trade, help the United States deal with global troublespots, and relax its heavy grip on dissidents and restive Tibet.
Republican presidential candidate Mitt Romney publicly blasted Obama's China policy and called the Democratic president's meetings with Xi "empty pomp and ceremony." It was a reminder that domestic crosscurrents on both sides of the Pacific can complicate attempts to stabilize Sino-American ties.
For his part, Xi mixed his vows of goodwill with reminders that China is impatient with U.S. arms sales to Taiwan - the self-ruled island that Beijing deems an illegitimate breakaway - and with Western sympathy for Tibetan resistance to Chinese control.
"History demonstrates that whenever each side deals relatively well with the issues bearing on the other side's core and major interests, then Sino-U.S. relations are quite smooth and stable. But when it is the contrary, there are incessant troubles," he said in his main speech in Washington.
Xi's more personable ways and familiarity with the United States - he has visited five times and his daughter is studying at Harvard - could make dealing with troubles easier than under Hu, but the problems will persist, said Kuhn.
"I don't look for any big change. It will be more style than substance," he said. "Across the whole range of issues, you can't expect any big changes. But in today's world, style can become substance, and that could make a difference."
HOPING FOR A COWBOY HAT MOMENT
For now, the outlook for Sino-American relations under Xi is masked by China's desire to avoid becoming even more of an electoral target during the U.S. presidential race and to smooth the way for a trouble-free Chinese political succession.
In his public comments, Xi has avoided hitting back at the Obama administration's complaints about the U.S. trade deficit and Beijing's strictures on political dissent. China's state-run media have cast his visit as a triumph of goodwill, and largely avoided reporting the barbs from Washington.
Instead, Chinese officials have drawn parallels between Xi's effort to woo the American public and the 1979 visit to the United States by the then de facto leader Deng Xiaoping, who oversaw the opening of diplomatic ties between the two nations.
Deng diluted wariness about China then by sporting a cowboy hat during a visit to Texas. Xi sought to reach out to the American heartland in a similar way in small-town Muscatine.
"My impression of the country came from you. For me, you are America," he told the people who had hosted him in 1985.
He recalled telling the daughter of his hosts, the Dvorchaks, about the Hollywood films he enjoyed, including "The Godfather", reported the China News Service.
"She was astonished and wondered how we could have seen so many American movies," recalled Xi.
"Although I stayed with the Dvorchaks for only two nights, they were two nights when I directly connected with the American people," he said. "That's something I'll never forget as long as I live."
That personal touch can help, said Carla Hills, a former U.S. trade representative, who met Xi in Washington.
"I think it's very tough to develop trust and willingness to cooperate unless you know the people on the other side and have confidence in them," said Hills.
"I sat next him at the luncheon," she added. "I think anyone who had tagged along behind him invisibly would have to say he did what he came to do. And that was to introduce himself."
Nowadays Chinese-U.S. relations are both far deeper and in many ways far more contentious than they were during Deng's 1979 visit or Xi's 1985 sleepover.
When Xi takes over from President Hu, he will inherit a list of disputes that will continue to irritate, if not inflame, relations. He will also confront a United States that appears less sure of its economic prospects and global pre-eminence.
In 2010, those disputes heated up into rancor between Beijing and Washington. China was angered with the Obama administration's decision to move ahead with arms sales to Taiwan, and also aggrieved by U.S. pressure about Internet censorship, human rights and Beijing's support for North Korea.
Both sides sought to cool the tensions, and since Hu's state visit to Washington in early 2010, Beijing has sought to mute disputes with the United States and its allies while it focuses on securing a trouble-free leadership succession.
Many in China, however, believe that their government should not bend to U.S. pressure and that Washington is to blame for U.S. economic woes and for many of the world's tensions.
Xi will inherit the Chinese Communist Party's collective, consensus-driven leadership, and it will be difficult for him to break with entrenched policies, even if he wants to. Hu could also try to keep some influence over foreign policy, like his predecessor Jiang Zemin.
"Successors normally can't establish or show what their views are, because they are still subordinate in a system run by others," said Roy, the former ambassador. "They can only show what their worldview is after they have taken the top position."
(Additional reporting by Paul Eckert and Doug Palmer; editing by Mohammad Zargham)