Almost all of the races that Democrats have lost in Florida have been winnable. None of the Virginia races in 2017/2018 were really winnable for Republicans so definitely the Florida Democrats.
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I think the last winnable race for the VA GOP was probably the 2014 Senate Race, the fundamentals are just too against them now.
On the other hand I think most races have been winnable for the FL Dems, at anyrate in 2018 the FL Dems threw away both the Senate race and Gubernatorial election by nominating Gillum for Governor. Had Gwen Graham been the nominee, the Democrats would have won the Governor's Mansion back and they would have held the Senate seat (Gillum dragged Nelson down imo).
This.
Florida's Democratic Party has become very much a regional party. It boasts very few elected officials outside of "South Florida" (the big Palm Beach, Broward, and Miami-Dade Counties), the Orlando area (Orange and Osceola Counties), the immediate Tallahassee area (Leon County, but not really the neighboring counties) and Gainesville (Alachua County). Hillsborough County (Tampa) is still Democratic, but it has a large GOP minority.
There are areas where Democrats have carried. Pinellas (St. Petersburg-Clearwater) and Duval (Jacksonville) counties are swing counties, but Pinellas still has mostly Republican legislators, and Duval's Democrats are mostly black (although Gillum DID carry Duval County, showing that nominating a black candidate to energize minorities isn't an entirely ridiculous strategy). There are some counties that are slowly trending Democratic (Manatee, Sarasota, and Seminole Counties come to mind), but these counties don't produce Democratic elected officials.
In many ways, the Democrats are where Florida's GOP was in 1976; they were competitive at the Presidential level, but had a depleted stable of candidates and were not likely to take over state government anytime soon. The Democratic candidate may well carry Florida in 2020, but it is hard to see either Rubio or Scott be dumped as Senator, and DeSantis looks like a strong bet for re-election at this point. None of that, however, precludes the Democrats from regaining lost ground in the Legislature, or in local offices. That's the hard work that Florida's Democrats seem to have slacked at. The number of close LEGISLATIVE races they've lost, even with decent candidates, is the most baffling aspect of Florida's politics.