Mr. Trump may also move quickly to renegotiate the North American Free Trade Agreement. He is scheduling meetings with the leaders of Canada and Mexico, the two main partners in that pact, which was negotiated by President George Bush and pushed through Congress by President Bill Clinton. While Nafta has been a major driver of American trade for nearly two decades, it has long been divisive, with critics blaming it for lost jobs and lower wages.

But free-trade advocates said that in canceling the Pacific pact, Mr. Trump lost an agreement that had already renegotiated Nafta under more modern rules governing intellectual property, internet access and agriculture, since both Mexico and Canada were signatories. He also undercut Mr. Obama’s so-called pivot to Asia and, critics said, essentially ceded the field to China, which was not part of the agreement.

“There’s no doubt that this action will be seen as a huge, huge win for China,” Michael B. Froman, the trade representative who negotiated the pact for Mr. Obama, said in an interview. “For the Trump administration, after all this talk about being tough on China, for their first action to basically hand the keys to China and say we’re withdrawing from our leadership position in this region is geostrategically damaging.”

Some Republicans agreed, but only a few would publicly challenge the president. Senator John McCain of Arizona called the decision “a serious mistake” that would hurt America. “It will send a troubling signal of American disengagement in the Asia-Pacific region at a time we can least afford it,” he said in a statement.

The Obama administration negotiated the trade pact for nearly eight years. Speaker Paul D. Ryan and other congressional Republicans worked with Mr. Obama to pass legislation granting so-called fast-track authority to negotiate it over Democratic objections. But Mr. Obama never submitted the final agreement for approval amid vocal opposition.

The agreement, the largest regional trade accord ever, brought together the United States and 11 other nations in a free-trade zone for about 40 percent of the world’s economy. It was intended to lower tariffs while establishing rules for resolving trade disputes, setting patents and protecting intellectual property.

Obama officials argued that it benefited the United States by opening markets while giving up very little in return. In particular, it finally brought the United States and Japan, the world’s largest and third-largest economies, together in a free-trade pact.