Most polls have the 2024 presidential race at a statistical tie, with Donald Trump having an edge against Joe Biden in most of the half-dozen or so swing states that will likely decide the outcome. But there’s another number in the contest that should alarm Biden. According to FiveThirtyEight’s average, Biden’s net approval average has reached an all-time low. Currently, 37.6% approve of the job he’s doing and 57% disapprove. That’s a net of nearly 20%. It comes a day after FiveThirtyEight’s forecast gave Biden “a 53-in-100 chance of winning the election” and “Trump still has a 47-in-100 chanc…