BRASILIA/MEXICO CITY (Reuters) - The presidents of Latin America’s two largest countries have held back from congratulating Joe Biden for winning the U.S. presidential election, even as other leaders of allied countries around the globe sent their best wishes.Biden, a Democrat, cleared the threshold of 270 Electoral College votes needed to win the presidency on Saturday, after four days of ballot counting following the Nov. 3 election. Incumbent Republican President Donald Trump has yet to concede. Brazil’s right-wing President Jair Bolsonaro had boasted he would be the first leader in the world to congratulate Trump, for whom he has often expressed admiration, on his re-election. But he has been silent on the matter in recent days. In Mexico, leftist President Andres Manuel Lopez Obrador reiterated he would not recognize the election winner until legal disputes were resolved, but said he had “no problem” with Biden. Trump has launched an array of lawsuits to press claims of election fraud, without producing evidence. State officials have said they are not aware of any significant irregularities. Lopez Obrador and Bolsonaro are part of a shrinking group of world leaders to not congratulate Biden that also includes Russia’s Vladimir Putin and China’s Xi Jinping.