BEIJING — President Xi Jinping of China looked regal as he stood in a limousine moving past Tiananmen Square this month, wearing a traditional suit of the kind favored by Mao and waving at parade troops assembled at attention. But the luster of Mr. Xi’s imperial presidency has dulled lately.

China’s economy has slowed more abruptly than policy makers have appeared ready for, alarming investors around the world. The governmentoverestimated its ability to keep stock prices aloft, spending billions to bolster the Chinese markets. Mr. Xi’s ambitious reform agenda, including an effort to revive a bloated state sector, has yielded few concrete results.

Often described as the most powerful leader of the Chinese Communist Party in generations, Mr. Xi is to arrive in the United States on Tuesday facing economic headwinds and growing doubts about his formula for governing — a sharp contrast with the image of unruffled control he projected when he hosted President Obama last year.

Yet he has shown no sign of retreating on an array of disputes that have bedeviled the Obama administration, including those about accelerated construction in disputed waters of the South China Sea and cyberattacks attributed to China that have targeted American businesses and government agencies. China has repeatedly denied having a role in those attacks.

Read the article “China’s Xi Jinping Arriving in U.S. at a Moment of Vulnerability” on nytimes.com.