The country’s leader, Gustavo Petro, backed down after a clash with President Trump, which started when Mr. Petro turned back U.S. military planes carrying deportees.

Mexican officials and other leaders in the region have not been able to meet with the incoming administration about its migration and deportation plans.

As the country’s top diplomat, Senator Marco Rubio of Florida, who has a special interest in Latin America, would be tasked with navigating Donald Trump’s efforts to expand U.S. influence.

In announcing his choice of various envoys, including ambassador to Denmark, the president-elect again floated the idea of the United States acquiring Greenland.