HONG KONG - When Hu Jintao visits the United States on Tuesday, he'll have a regal entourage of aides, bodyguards and limousines. But the Chinese leader will leave behind in Beijing the most potent totem of his power: the title of general secretary of the Chinese Communist Party.

He's not giving up his day job as head of the world's largest political organization, but during his four-day U.S. trip, he'll assume an alternative identity. He'll be greeted at the White House and a Chicago auto-parts factory as Mr. President, a made-for-export alias used mostly for encounters with foreigners.

The morphing of roles flows from the protocol of his mission. Hu travels to the United States to represent China as a nation, not just its ruling party. But the shift obscures the true nature, and also curious limitations, of Hu's authority - his stewardship of a sprawling party apparatus that stands above all formal institutions of government but is no longer a rigid monolith obedient to a single leader. It also helps explain why Washington often has so much trouble figuring out who is making decisions in Beijing and why.

At a time when China looms increasingly large in U.S. economic and security concerns, the distribution of power in Beijing, as well as in Washington, will decide whether the pledges of cooperation that will be made next week by President Obama and the Chinese leader take solid form, or quickly dissolve, as many did after Obama's trip to Beijing in November 2009.

After a tense year that saw frequent verbal clashes between Washington and Beijing on everything from trade and currency to North Korea and the South China Sea, Hu is seeking to reaffirm China's position as a rising power but also to calm fears over its intentions. The trip "is intended to put the toothpaste back in the tube and stabilize the relationship," said Aaron Friedberg, a Princeton University professor and a former security affairs adviser to Vice President Dick Cheney.

As China has grown stronger and wealthier, however, its leadership has grown more diffuse and harder to locate, and in some ways even weaker.

"China is no longer ruled by a strong man a la Mao [Zedong] or Deng Xiaoping, but by a collective oligarchy," said Susan Shirk, a deputy assistant secretary of state in the Clinton administration.

The diffusion of authority, which has accelerated steadily since the death of Deng in 1997, reflects both the growing complexity of society and governance and the personalities of senior leaders forged not by revolutionary struggle, but by the give-and-take of bureaucratic consensus.

The party, with some 80 million members, still blankets China and swiftly snuffs out direct challenges to its authority, but is itself a collection of different and often competing interests. It is not held together by ideology but by the glue of nationalism, a force that ranges from low-key pride in China's past and current achievements to strident jingoism.

"The U.S. always hoped that China would become more diversified," said Jin Canrong, vice dean of the School of International Studies at People's University in Beijing. This is now happening, and the United States "has got to get used to it." Competing voices mean that Chinese decision-making on foreign policy "will be more and more like that in the U.S. in the future."

A big difference, however, is that some of China's most powerful voices are heard only in secret. "This is one of the great frustrations and paradoxes about China," Shirk said. "It has a vibrant market economy that is open to the world, but a decision-making process that is very, very opaque."

Power structure

America's confusion extends to Hu himself, who stands at the apex of a highly centralized party structure but is sometimes kept in the dark and even defied by those he nominally controls, particularly the People's Liberation Army. In a meeting last Tuesday with visiting Defense Secretary Robert M. Gates in Beijing's Great Hall of the People, for example, Hu seemed unaware that his military had just tested a stealth fighter jet. "Is this true?," he asked Defense Minister Liang Guanglie, according to a senior U.S. official.

On North Korea, Chinese policy is guided by clear national interests, such as a desire to prevent a tidal wave of desperate refugees crashing across its border, but also by long and intimate relations between China's Communist Party and the Korean Workers' Party. Beijing's day-to-day dealings with Pyongyang are handled not by the Foreign Ministry but by the party's International Liaison Department.

"For us, China's decision-making on North Korea was always a black box. There was the party, the Foreign Ministry and the military," recalled Victor Cha, who served as a Korea expert on the National Security Council in the Bush administration and traveled to Beijing for now-suspended six-party talks on Pyongyang's nuclear program. Chinese diplomats "are the ones that show up at the table, but I don't think they steer overall policy."

U.S. officials, Cha said, have frequent and often constructive contacts on North Korea with the Chinese Foreign Ministry but none with the party department directly responsible. "I don't recall ever meeting the party," said Cha, a senior fellow at Washington's Center for Strategic and International Studies.

There is also a cacophony of views on currency policy, which, despite some changes, Washington insists is still unfairly skewed to boost Chinese exports and which will likely be a major issue during Hu's visit. The People's Bank of China, the country's central bank, favors a stronger yuan, something the U.S. has long demanded. This would, among other things, help calm inflation, now a major concern for leaders, by reducing the price of foreign foods and other imports. But the central bank has little of the independence enjoyed by the U.S. Federal Reserve to fix policy.

The Commerce Ministry, focused on keeping China's export juggernaut roaring, fiercely resists any sharp rise in the value of the Chinese currency, which would make Chinese goods more expensive abroad. It casts itself as a bulwark of patriotism against foreign pressure.

The State Council, or cabinet, adjudicates, but the final decision is thought to rest with the Standing Committee of the Politburo, whose agenda, deliberations and decisions are secret. "We have a pretty good handle" on the general decision-making process, said Victor Shih, a scholar of China's political economy at Northwestern University, "but nobody can know who makes a particular decision."

'A lot of players'

The party and state often overlap, as in the case of Hu, who, like his predecessor, Jiang Zemin, is both general secretary and "state chairman," a title that China renders into English as "president." He's also head of the Central Military Affairs Commission, a party body that is far more important than the largely powerless Defense Ministry, which hosted Gates's trip to China.

The mixing of functions makes it difficult for outsiders to locate where exactly policy is set, particularly as the party, while far removed from its Marxist roots, retains many of the secretive habits of its origins as an underground organization. The recent appointment of a high-ranking official as party secretary for the Foreign Ministry, for example, spurred debate among tea-leaf-reading China watchers over whether he, or the minister, is really in charge.

"The reality is that in foreign affairs, as in other areas, there are a lot of players. Coordination is not their strong suit," said Kenneth Lieberthal, a scholar at the Brookings Institution who served as a China expert in the Clinton administration.

Both Beijing and Washington hope that Hu's visit will soothe recent tensions that, according to Jia Qingguo, vice dean of Peking University's School of International Studies, left both sides worried about the risk of "more and bigger conflicts" in the future.

But with Hu due to step down next year in favor of Xi Jinping, a fellow member of the Politburo Standing Committee, commitments made in Washington next week could buckle under the pressure of a political transition that may embolden more nationalist, anti-American forces.

China's senior leaders are all "very cautious" and don't want unscripted upsets, said Friedberg, the Princeton professor. But in a system that is closed but also surprisingly open to competing pressures, including public opinion, "maybe being assertive, unapologetic and truculent is the best, most cautious place for them to be."

Researcher Zhang Jie in Beijing contributed to this report.