* 19th Communist Party Congress starts Oct 18
* Xi allies expected to be promoted
* Expectations are that Xi will be given new titles
BEIJING, Oct 16 (Reuters) - Chinese President Xi Jinping is set to amass even greater power at a Communist Party Congress this week, promoting close allies, having his guiding thought enshrined in the party constitution and possibly assuming a title to put him on par with Mao Zedong.
That is the view of multiple sources with ties to the Chinese leadership, including senior party officials, former officials and foreign diplomats who have talked to top officials. Much of it has also been signalled in various ways in the state media in recent months.
Xi was born into revolutionary aristocracy and came of age in the tumult of Mao's Cultural Revolution. Since taking office five years ago, he has cast aside decades of precedent, stamping his authority on the party's 89 million members and asserting China's rising might on the global stage.
Having been perceived as a colourless, unambitious "princeling" child of the elite before catapulting into the apex of power as a Standing Committee member in 2007, Xi has surprised time and again, leadership sources, diplomats and experts say. He has locked up political rivals for corruption, accumulated titles and pushed painful reforms for the military.
China's State Council, which doubles as the party's spokesman's office, did not respond to a request for comment on Xi's plans for the 19th Party Congress or on how the party evaluates his first five years in office.
At the congress, a twice-a-decade event that opens Wednesday, some of Xi's most trusted aides look set for promotion to the Standing Committee, such as Li Zhanshu, an advisor who worked as a junior official in Hebei province in the 1980s at the same time as Xi.
In another key break with tradition, Xi looks set to retain a key ally, Wang Qishan, in some capacity despite the anti-corruption tsar passing retirement age.
Xi could also end up being called party chairman, a role that would pave the way for him to stay in office past 2022 when precedent dictates he should step down, leadership sources say.
"Xi is now moving more in the direction of a king, of 'I am China' and 'I am the Communist Party"', said Steve Tsang, director of the China Institute at the School of Oriental and African Studies in London.
In another first, Xi has already overseen two large-scale military parades in his first term, including a dramatic display of China's rising power and military capability through Beijing's Tiananmen Square in 2015.
What will actually happen at the congress, and what Xi will say in his state-of-the-party address at its opening, are closely guarded secrets, even as the party and state media have flagged the broad outlines of what will happen.
One of the most important signals to watch at the congress will be whether - or how often - Xi is referred to as "lingxiu", or leader. That honorific has been bestowed only on two others since the 1949 founding of the People's Republic of China: Mao and his short-lived successor, Hua Guofeng.
Using the term over the congress could set him up to be named party chairman, a title that has not been used since Hu Yaobang, who died in 1989, sources with ties to the leadership and diplomats say.
Xi is currently head of the party but with the title general secretary, and has to rule by consensus with his Standing Committee, part of a system of collective leadership set up after Mao died to prevent a recurrence of the chaos that erupted under him.
If he does become chairman, that will spell the end for the concept of collective leadership, said a senior Beijing-based Asian diplomat.
"He won't have to answer to anyone," the diplomat said.
Xi has gathered other titles gradually since late 2012, when he first became party chief, just before assuming the presidency. He also runs the National Security Commission and the top financial and reform decision-making councils. And despite already being head of the military, he was appointed commander-in-chief last year.
Arguably one of China's crowning achievements over the past five years, one unquestionably popular with the public, has been Xi's crackdown on corruption. Some 1.4 million officials have been punished and many jailed, including the much feared former domestic security chief, Zhou Yongkang.
Xi has also cracked down on the pomp that had previously gone with visits by high-level Chinese officials to the provinces, and flashed a deft common touch to show his connection to the ordinary person.
In one widely-reported instance, Xi visited a Beijing dumpling restaurant in late 2013; images on state media showed him lining up for his food with other patrons.
"Part of the story of Xi's rising personality profile is about the need to bolster the perceived legitimacy of the Communist Party around a leader seen as being of the people," said David Bandurski, co-director of the China Media Project.
He said the previous leadership of President Hu Jintao and Wen Jiabao had warned of a growing gap between the Communist Party and the rest of the country, partly epitomised by rampant corruption.
"So under Xi there was an immediate move to address both of these key problems of perception", Bandurski said. "The answer was Xi as the plain-talking man of the people."
(Additional reporting by Benjmain Kang Lim, Christian Shepherd and Michael Martina; Editing by Philip McClellan)