In other action on a busy opening day, Mr. Trump ordered a hiring freeze in the federal workforce, exempting the military. And he reinstituted limits on nongovernmental organizations that operate overseas and receive American taxpayer money from performing abortions. Republican presidents typically impose those restrictions soon after taking office, and Democratic presidents typically lift them when they take over.
The president’s withdrawal from the Asian-Pacific trade pact amounted to a drastic reversal of decades of economic policy in which presidents of both parties have lowered trade barriers and expanded ties around the world. Although candidates have often criticized trade deals on the campaign trail, those who made it to the White House, including former President Barack Obama, ended up extending their reach.
“We’ve been talking about this for a long time,” Mr. Trump said as he signed a document formalizing his decision. The withdrawal from the trade pact, he added, is a “great thing for the American worker.”
Aides signaled that Mr. Trump may also move quickly on renegotiating the North American Free Trade Agreement. He is scheduling meetings with the leaders of Canada and Mexico, the two main partners in that pact, first negotiated by the elder President George Bush and pushed through Congress by President Bill Clinton. Nafta has been a major driver of American trade for nearly two decades, but it has long been divisive, with critics blaming it for lost jobs and lower wages.
Mr. Trump outlined his views in his Inaugural Address on Friday, when he promised an “America First” approach to the world. “We must protect our borders from the ravages of other countries making our products, stealing our companies and destroying our jobs,” he said. “Protection will lead to great prosperity and strength.”
He said that his policy would be to “buy American and hire American.”
The Obama administration arduously negotiated the Pacific trade pact over eight years. Under legislation passed by Congress, the accord could not be amended once completed, nor could it be joined without congressional approval. Mr. Obama never submitted the partnership for approval, understanding that a defeat in Congress would be worse than leaving the deal in hibernation.
In discarding the Trans-Pacific Partnership, or T.P.P., Mr. Trump tacked away from his Republican allies in Congress who have long supported such trade agreements. Speaker Paul D. Ryan worked closely with Mr. Obama to pass legislation granting the president so-called fast-track authority to negotiate the trade agreement over the objections of many Democrats. But amid opposition, Congress never approved the deal itself.
The agreement brought together the United States and 11 other nations along the Pacific Rim, including Canada, Mexico, Japan, Vietnam, Malaysia and Australia, creating a free-trade zone for about 40 percent of the world’s economy. It was intended to lower tariffs while setting rules for resolving trade disputes, setting patents and protecting intellectual property.
Mr. Obama and his Republican allies argued that the pact would open growing foreign markets to American businesses. But Democrats, ultimately including Hillary Clinton, even though she had helped push negotiations forward as secretary of state, said it would benefit wealthy corporations at the expense of workers and the environment.
Mr. Trump sided with them, and he beat Mrs. Clinton in crucial Midwestern industrial states like Michigan and Wisconsin that had traditionally gone Democratic but have been hurt by changes in manufacturing over recent decades.
The president’s action on the deal came the same day he met with business leaders in the morning and was set to speak with union leaders in the afternoon. He will also meet with congressional leaders of both parties and hold a separate meeting with Mr. Ryan.