HANOI, Vietnam -- Vietnam's ruling Communist Party began an eight-day congress Thursday that starts an orchestrated transfer of power to new leaders who will face myriad challenges including economic reforms, corruption and maritime aggression from China.

Despite the veneer of renewal, the new leadership will be drawn from a limited pool of officials within party ranks and is expected to be led by the same man who has been at the top for the last five years, General Secretary Nguyen Phu Trong.

"Corruption and wastefulness remain serious problems ... causing discontent in the public, affecting people's trust in the party and the state," Trong warned in his speech to open the congress of 1,510 delegates, representing Vietnam's 63 provinces, ministries, and other party organizations.

In a reference to China, which has been expanding its influence in South China Sea to the dismay of its neighbours, Trong said the "complicated developments in the East Sea" and other economic problems have "negatively affected our country."

Vietnam is one of the last remaining communist nations in the world, with a party membership of 4.5 million, but like its ideological ally China, the government believes in a quasi-free market economy alongside a strictly controlled society that places several restrictions on its 93 million people.

Delegates stood and clapped when Trong and 15 other Politburo members walked into the conference hall at the National Convention Center near the city centre. The stage was set against the backdrop of a bust of the country's revolutionary leader, Ho Chi Minh, portraits of Karl Marx and Vladimir Lenin, and the national flag and the hammer-and-sickle red flag for the party.

Delegates also sang the national anthem and "L'Internationale," the official song of communism.

The Communist Party is constitutionally empowered to run the country. It names a new crop of leaders every five years, but the process is shrouded in secrecy. The congress will end Jan. 28 when the names of the general secretary, the prime minister, the president, the chairman of the National Assembly and other top functionaries will be announced.

Their appointments would have been already decided, and the delegates would simply endorse them. The most crucial position is general secretary, the de facto No. 1 leader of the country, although Vietnam professes a collective leadership through a Politburo that handles day to day affairs, and a larger Central Committee that meets twice a year to decide policy.

Although the entire process is stage-managed, Trong faced a challenge this time from Prime Minister Nguyen Tan Dung (pronounced New-yen Taan Dzoong), who has spearheaded economic reforms with mixed success. Although he is seen as pro-business and reform minded, he was also accused of economic mismanagement, nepotism and promoting patronage politics by favouring party members in return for political support.

On Wednesday, it seemed clear that Trong had sidelined Dung when a preparatory meeting agreed to continue with a controversial 2014 rule barring all but officially nominated candidates from consideration, with no new nominations allowed from the congress floor. Trong was endorsed as the general secretary candidate earlier this month.

However, there was a strong belief that Dung would not go down without a fight, and a complicated interpretation of the rules given to Vietnamese journalists by Minister of Information and Communications Nguyen Bac Son on Thursday suggested his case might not be hopeless.

Son said that while the 175 members of the party's Central Committee were barred in the congress from nominating themselves or others, and from accepting a nomination, other delegates were not restricted from doing so. A Central Committee member such as Dung would be obliged by the rule to refuse nomination, but delegates could reject his refusal, said Son. Such a scenario could set up a showdown with Trong.

However, going into the congress, the two camps were believed to have reached a compromise under which Trong would stay as general secretary for two years instead of five, and a Dung supporter would become the chairman of the National Assembly. The prime minister's post would go to a neutral person and the president would be a Trong loyalist.

This configuration "would be a demonstrable loss for Dung" but it should not be "confused with an outright win by Trong," said Christian Lewis, a Vietnam expert at the New York-based Eurasia Group think-tank . "It is instead a composition that reflects a desire for a balance and more consensus-driven decision-making at the very top," he wrote in a commentary.

Dung's apparent ouster "represents a clear vote by the top leaders in favour of balance over strong personalities in the make-up of the Politburo," Lewis wrote.

The development raises questions about the direction of economic reforms Dung had been backing. The reforms have brought a flood of foreign investment, created a fledgling stock market and helped triple per capita GDP to $2,100 over the past 10 years, but his rivals accuse him of economic mismanagement and failing to control massive public debt and non-performing loans of state-owned banks.

But, Lewis said, the new set of leaders will support the current economic reforms and trade policy. Notably they remain committed to the Trans-Pacific Partnership with the United States and other key trade deals including the free trade agreement with the European Union.

"Vietnam wants to diversify its economic partners to avoid becoming excessively dependent on China," Lewis said.

Vietnam has an ambivalent relationship with China. Despite being its largest trading partner, China is also a security challenge. Beijing has been expanding its territorial assertions in the South China Sea, but Vietnam has pushed back against those claims. Dung has been seen as standing up to Beijing, not afraid to criticize it, while Trong was seen as being soft on China.

Still, the new leaders will be particularly positive for U.S.-Vietnam relations, said Lewis, pointing out that Trong's visit to the U.S. in July 2015 was well received.

Over the next week, the congress will review and set national and party policies, and select a Central Committee. On one of the last days of the congress, the new Central Committee will meet to select a Politburo from among its ranks and pick one of them as party general secretary.

The country's three other top leaders -- prime minister, president and National Assembly chairman -- would be named at the congress, but their actual selection will be done by the National Assembly, which itself is elected about six months after the Congress.

Associated Press writers Tran Van Minh in Hanoi, and Vijay Joshi and Grant Peck in Bangkok contributed to this report.