Although the deal had not been approved by Congress, the decision to withdraw the American signature at the start of President Trump’s administration is a signal that he plans to follow through on promises to take a more aggressive stance against foreign competitors.

WASHINGTON — President Trump planned to formally abandon the Trans-Pacific Partnership on Monday, pulling away from Asia and scrapping his predecessor’s most significant trade deal on his first full weekday in office, administration officials said.

Mr. Trump sharply criticized the partnership agreement during last year’s campaign, calling it a bad deal for American workers. Although the deal had not been approved by Congress, the decision to withdraw the American signature at the start of Mr. Trump’s administration is a signal that he plans to follow through on promises to take a more aggressive stance against foreign competitors.

He may also talk about renegotiating the North American Free Trade Agreement and 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.