Doubt is setting in among senior Democrats, including some of President Joe Biden’s aides, about his strategy for winning re-election. Biden’s core inner circle remains confident in reminding voters about the Jan. 6 insurrection, political violence, threats to democracy and Donald Trump’s character, which the president and longtime aide Mike Donilon believe will be the key to winning. Yet he’s been consistently falling behind in polls, reported Axios. “It is unclear to many of us watching from the outside whether the president and his core team realize how dire the situation is right now, and …