The promises Joe Biden made as a candidate fall roughly into two categories: those easy to carry out in his first days in the Oval Office, and those that will be exceedingly difficult no matter how long he tries. Because many of President Donald Trump’s initiatives were accomplished by executive order, Biden can undo them with the stroke of a pen. But his bolder ideas face uphill battles in the U.S. Senate, where his fellow Democrats will hold the narrowest majority possible. Here’s a partial ta