Interestingly... I think it's covid that has seen Trump off. He disputed and maligned mail in votes (despite the fact he has used mail in all the time).
From an article...
the president has spent months undermining vote-by-mail’s integrity, despite members of his own campaign and administration, along with election watchdogs and the FBI, finding no evidence of widespread fraud – his supporters have echoed those claims, while Democrats have urged voters to cast their ballots safely by mail ahead of Election Day.
A number of states were not legally permitted by their Republican-controlled legislatures to process mail-in ballots until Election Day, and with potential surges in mail-in ballots amid the public health crisis and Democratic urgency, election workers have experienced delay producing results.
In recent litigation in Pennsylvania ahead of Election Day, the president’s re-election campaign also could not produce any evidence of vote-by-mail fraud.
A federal judge ordered the campaign to “produce such evidence in their possession, and if they have none, state as much”. In more than 500 pages of court filings, it produced evidence pointing to only a handful of election fraud cases, none of which involved mail-in ballots.