Way back early 2010's I read an article making a good argument that there really is no "swing vote". With almost half the population not bothering to vote what looks like swing vote is actually voter activation.

Some candidates energize their "base" better than others, some even excite people who normally don't vote to go trough registration, suppression, gerrymandering and queuing to have their say.

Oddly enough, it seems to be Mr. Trump activating voters both for him and against him. Mr. Biden really doesn't seem to be able to energize even his own synapses at times.