Under the red-starred dome of the Great Hall of the People in Beijing, nearly 3,000 delegates of the National People’s Congress, the party-controlled legislature, voted to approve an amendment to the Constitution to abolish the term limit on the presidency, opening the way for Mr. Xi to rule indefinitely.

The vote approved a list of amendments that also included updating the Constitution with salutes to Mr. Xi and his drive to assert party supremacy.

Ever since the party said two weeks ago that it wanted to remove the 35-year-old line in the Constitution limiting the president and vice president to two consecutive terms, there was never any real doubt that the congress would approve the move. But the lopsided outcome — 2,958 votes in favor, two against and three abstentions — underlined how much Mr. Xi dominates politics and feels emboldened to demand drastic change.