They acknowledge that it may be difficult to convince the Trump administration to invest large sums in the region, a proposal they have only recently broached with American officials.

Buy they are hoping the perceived threat of China’s growing presence in the region can be used as leverage to bring the United States on board.

While it is unclear how much more China would be willing to invest in the region, in recent years it has increased its presence throughout Latin America, financing infrastructure projects, tightening ties with governments and even convincing a handful of Central American nations to switch their diplomatic recognition of Taiwan to China — a sticking point with the Americans.

The Mexican strategy to rely on the United States’ concerns about China’s expanding influence in the region reflects a growing sense in Mexico that it can no longer take cooperation with the United States for granted.

Both the White House and State Department declined to comment on the Mexican proposal.

“For a long time there has been this competition within Latin America for influence, where China is willing to invest billions in infrastructure and energy that the United States simply isn’t,” said Duncan Wood, the director of the Mexico Institute at the Wilson Center.

The proposal is also a reflection of the distinct personalities of Mr. López Obrador and Mr. Trump: Both are mavericks — albeit on opposite sides of the political spectrum — and both are willing to break with long-established conventions.