Nikki Haley and Ron DeSantis, once fierce rivals of former US president Donald Trump in the race for the Republican presidential nomination, used their speeches at the party’s national convention to reaffirm he now has their full backing. “I’ll start by making one thing perfectly clear. Donald Trump has my strong endorsement,” Haley told the crowd at the Republican National Convention in Milwaukee, Wisconsin on Tuesday. Trump was officially nominated as the Republican Party’s presidential candidate for November’s elections on Monday. Haley, who was received with a mix of cheers and booing, dro…