WUHAN, China — Throughout much of China’s economic rise over the past three decades, one Chinese official quietly played a pivotal role in pushing an embrace of free markets.

That official, an urbane central bank official named Zhou Xiaochuan, is widely expected to retire soon. His replacement may be unwilling or unable to follow in his footsteps, leaving uncertain whether China will tackle problems that could threaten its growth.

That transition, which could take place amid a broad reshuffling of senior Chinese leaders in the coming months, would have implications inside and outside China. Mr. Zhou’s successor will play a central role in managing the financial system of the world’s second-largest economy — a system that experts say is still plagued with heavy debt and onerous government control. The next governor of China’s central bank will also have a say in how China manages its currency, a lingering political issue for President Trump and other leaders of China’s major trading partners.

Potential candidates so far include a provincial leader who is a Communist Party stalwart, a top banking regulator, and Mr. Zhou’s top deputy, among others. But any successor will face challenges working for Xi Jinping, China’s president, who appears determined to reassert control in a financial sector that Mr. Xi’s allies see as needing more government control, not less.