BRASÍLIA—U.S. Commerce Secretary Wilbur Ross laid out a plan including credit and investment to help rebuild Venezuela’s economy under democratic rule, as Washington pushes for new leadership in the struggling nation.

The American plan is contingent on the removal of Venezuela’s authoritarian leader, President Nicolás Maduro, and his replacement with Juan Guaidó, leader of a fractious opposition supported by the U.S. and other countries.

Speaking...