Secretary of State Cordell Hull (D-TN) / Postmaster General James Farley (D-NY) ✓
Businessman Wendell Willkie (R-IN) / Senator Charles McNary (R-OR)
Avoiding the third term issue is probably Hull's only advantage over Roosevelt. He has Roosevelt's full blessing for his internationalist stance, of course, and a prominent New Dealer ends up on the ticket to shore up the Northeastern bosses and address Roosevelt's concerns about safeguarding his domestic policies. But other than that, Hull was old and sick and reluctant even just to keep being Secretary of State, and Democratic factionalism would simmer more with the change in faces (a Southern president might give the black community pause, while white Southerners would notice that he doesn't race-bait). The America Firsters would be spooked by such insistence on picking an internationalist, which would be felt especially in the Midwest. Putting a Catholic on the ticket in Farley would also hurt the ticket in some places (e.g. Utah). I do think he holds up in the Northeast with his strong internationalism and, again, Farley on the ticket. All in all, it would be a tighter race, but still not too close with just how badly Republicans had screwed up in recent memory.