MEXICO CITY (Reuters) - Mexico’s president on Tuesday congratulated U.S. President-elect Joe Biden on his election victory, ending weeks of waiting that generated sharp rebukes from allies of Biden who said the delay threatened to harm bilateral relations. At his daily morning press conference, President Andres Manuel Lopez Obrador said he sent the incoming American leader a letter praising Biden’s “triumph” after he was certified on Monday as winner of the state-by-state Electoral College vote that officially determines the U.S. presidency. The two-page letter, dated Dec. 14, was quickly published on social media by Mexican officials. Lopez Obrador’s recognition of Biden’s win over President Donald Trump confirmed Reuters reporting from last week that the Mexican leftist would wait until the victory was affirmed by the electoral vote. For weeks following the Nov. 3 U.S. election, Lopez Obrador was part of a shrinking club of world leaders who declined to recognize Biden, repeatedly arguing it was prudent to wait until Trump’s legal challenges ended. Russia’s President Vladimir Putin congratulated Biden just a few hours before Lopez Obrador. Brazil’s President Jair Bolsonaro has yet to recognize Trump’s loss. Mexico’s delay led to a growing chorus of criticism from U.S. Democrats, including high-ranking members of Congress, who said the Mexican leader’s caution could do long-lasting harm to relations. In his letter, Lopez Obrador stressed Biden’s pro-immigrant stance and suggested working together on the thorny issue, following years of Trump’s unprecedented threats to do more to reduce the flow of U.S.-bound migrants from Mexico. “I also want to express my recognition of your position in favor of Mexican and the world’s migrants, which will allow the continuation of our plan to promote development and well-being in southeast Mexico and among the countries of Central America,” Lopez Obrador wrote. He also called for the two countries to work together while respecting each other’s sovereignty.