Trump does not have forever, or even until Election Day. He has to have a lead greater than the margin of fraud, and he needs it in enough swing states before early voting starts.
When you said “He has to have a lead greater than the margin of fraud” it immediately made me think: “When was the last time a Democrat was concerned about a Republican candidate committing voter fraud?” This of course can be expanded to questioning whether or not there are any demorat concerns about republican voter fraud tactics in general.
Bottom line: Everybody seems to know that the fraud is pretty much exclusively committed by the left. It’s a truism that no one denies.