Not at all the same comparison. Republicans ran two extremely WEAK opponents against Obummber - loser/apologist/RINO John McCane ('08 - but Sarah Palin was a great choice for VP) and loser/apologist/RINO Mitt Romney ('12 - loser Paul Ryan never have a chance).
The only way Biden/Harris win in '20 is by popular vote fraud through ballot stuffing. Trump's popularity, American pride, Patriotism, Swamp draining, exposed China/Russia/Ukraine corruption of Biden, and the economy (right now), regardless of Covid, will carry the day for a Trump/Pence administration through '24. Covid will die on November 4th as there will be no political horse to ride for the Dems after their defeat.