FDR dies in 1940, before Election Day

  Probably not overall although presuming other things go as OTL he would be very likely to support the Soviets at least as much as Roosevelt.  Presuming that things go pretty much as OTL.

  Could depend on when in 40 Roosevelt dies, for instance if its before his formal nomination or before he selects Wallace as his vice President Wallace may never get the opportunity and someone else is the Democrat candicate.  I notice that from his wiki entry, Henry_A._Wallace, as a relatively young and inexperienced politician and a former Republican Wallace was an unpopular choice and Roosevelt had to threaten to decline the nomination unless Wallace was accepted as his VP. 

  Unless there's a serious split in the Democrats, which there might be if Roosevelt died while seeking to get Wallace excepted and a messy struggle for the Presidential nomination result I would expect them to defeat the Republicans.  There is likely to be a sympathy vote for the dead President plus they have brought the country out of the depth of the depression and with growing tension/crisis in Europe and the Far East there would probably be a reluctance to change horses at such a time.