I don't think it matters that much if he promised or not. What matters is the thing itself, which is why it was an issue in 2020 and why it's an issue now. This unnamed advisor is probably right.
ABC/WaPo/Ipsos (A+ pollster with a D+0.8 average bias) finds that 62% of Democrats and leaners, including 54% of Biden supporters and a 49% plurality of black voters, think Biden should step aside
A separate thing, not related to this case but which I think is interesting, is that 538's economics-based fundamentals are reasonably chosen but questionable based on the observed divergence between conditions and sentiment. The polls haven't followed the path the fundamentals would predict
There actually doesn't seem to be a big racial gap among Democrats on whether Biden should drop out. Black voters, who are overwhelmingly Democrats, say 42% yes, and the party as a whole is at 45%. These are really bad numbers for an incumbent.
Rather than extending DC Metro, I'd build more branches along with infill stops in DC. Something like this. Assume the yellow lines are re-extended north and the blue is deinterlined with a rail shuttle between Rosslyn and Pentagon.
