So while researching another topic I ran across a reference to early opposition by FDR to handing over even mothballed reserve destroyers to the UK in 1940 - which he eventually dropped.
Let's say that the PoD is FDR deciding he can't afford the political capital to transfer US warships to the UK with an election coming up. He blocks the deal, and DD for Bases never happens.
Destroyers for Bases was the first in a series of belligerent acts by the US towards Germany; absent that first step, is Lend-Lease delayed or reduced? The US will continue to sell weapons to the Allies, mind, just not the loan and lease arrangements of OTL.
FDR will probably take some other steps to help the Allies; what does he come up with, and when are these steps taken?