BEIJING (AP) - President Xi Jinping is poised to make a historic power grab as China's legislators gather beginning Monday to approve changes that will let him rule indefinitely and undo decades of efforts to prevent a return to crushing dictatorship.

This year's gathering of the ceremonial National People's Congress has been overshadowed by Xi's surprise move - announced just a week ago - to end constitutional two-term limits on the presidency. The changes would allow Xi, already China's most powerful leader in decades, to extend his rule over the world's second-largest economy possibly for life.

"This is a critical moment in China's history," said Cheng Li, an expert on elite China politics at the Brookings Institution in Washington.

In this Saturday, March 3, 2018, photo, Chinese President Xi Jinping, center, arrives with Premier Li Keqiang, left, for the opening session of the Chinese People's Political Consultative Conference in Beijing's Great Hall of the People. Xi is poised to make a historic power grab as China's legislators gather from Monday and prepare to lí do approve changes that will let him rule indefinitely and undo decades of efforts to prevent a return to crushing dictatorship. (AP Photo/Ng Han Guan)

The move is widely seen as the culmination of the 64-year-old Xi's efforts since being appointed leader of the ruling Communist Party in 2012 to concentrate power in his own hands and defy norms of collective leadership established over the past two decades. Xi has appointed himself to head bodies that oversee national security, finance, economic reform and other major initiatives, effectively sidelining the party's No. 2 figure, Premier Li Keqiang.

Once passed, the constitutional amendment would upend a system enacted by former Chinese leader Deng Xiaoping in 1982 to prevent a return to the bloody excesses of a lifelong dictatorship typified by Mao Zedong's chaotic 1966-1976 Cultural Revolution.

"Deng Xiaoping's abolishment of lifetime tenure for the leadership and more institutionalized transitions in power are very much in question," said Li, the politics expert.

Passage of the proposed constitutional amendment by the congress' nearly 3,000 hand-picked delegates is all but certain.