Philly has the largest fraud machine in the country. They can get a potato elected.
Even Philly fraud needs to build on a base level of legal votes. Normally there are also a lot of, alas legit, liberal votes coming out of Philly along with the extra fraud. If their base is dispirited and doesn’t vote, or worse votes GOP, its harder to win with the fraud alone. I’m sure thinking about “win one for Fetterman and Biden” will amp that base.