evidence: Former President Donald Trump and President Joe Biden debate at CNN's Atlanta studios on June 27. President Joe Biden’s campaign has worked feverishly behind the scenes to keep the Democratic wagons circled around the president, with advisers taking note of any current or former elected officials speaking ill of the president or publicly suggesting he should step aside. [...] For years, the relationship between Obama and Biden and their circle of advisers was strained by Obama’s decision to support Hillary Clinton’s presidential bid in 2015 and urge his former vice president not to run. This moment "is even more fraught," one longtime Obama adviser said Saturday.