MEXICO CITY—Mexican President Andres Manuel Lopez Obrador said on Saturday he would not congratulate a winner of the U.S. presidential election until legal challenges are concluded. The Associated Press decision desk projected a victory for Democrat presidential candidate Joe Biden in the battleground state of Pennsylvania on Saturday, pushing him over the threshold of 270 Electoral College votes. Confirming the winner of the Electoral College, which decides the formal winner of the U.S. presidential race even if the media declares a winner or a candidate concedes, is a process that can take the states and Congress up to two months to complete....