BEIJING — On one of his many visits abroad in recent years, Xi Jinping, the presumptive new leader of China, met in 2009 with local Chinese residents in Mexico City, where in a relaxed atmosphere he indirectly criticized the United States.

“There are a few foreigners, with full bellies, who have nothing better to do than try to point fingers at our country,” Mr. Xi said, according to a tape broadcast on Hong Kong television. “China does not export revolution, hunger, poverty nor does China cause you any headaches. Just what else do you want?”

Mr. Xi is set to be elevated to the top post of the Chinese Communist Party at the 18th Party Congress scheduled to begin here on Nov. 8 — only two days after the American election. He will take the helm of a more confident China than the United States has ever known. He will be assuming supreme power in China at a time when relations between the two countries are adrift, sullied by suspicions over a clash of interests in Asia and by frequent attacks on China in the American presidential campaign.

In the last four months, China has forged an aggressive, more nationalistic posture in Asia that may set the tone for Mr. Xi’s expected decade-long tenure, analysts and diplomats say, pushing against American allies, particularly Japan, for what China considers its territorial imperatives. The son of a revolutionary general, Mr. Xi, 59, boasts far closer ties to China’s fast-growing military than the departing leader, Hu Jintao, had when he took office. As Mr. Xi rose through the ranks of the Communist Party, he made the most of parallel posts in the People’s Liberation Army, deeply familiarizing himself with the inner workings of the armed forces.