They can't. Middle class oil workers, workers in the gasoline auto-sector will not vote for Democrats. The same goes for many who are contractors; plumbers, electricians, HVAC.
Those working for Amazon might be able to unionize, same with Walmart. Hopefully they can get better pay, and hours. But they are not fighting the same fight as climate activists.
Trump might break teacher unions soon with school vouchers.
Democrats need to start with hyper-local issues, and organize around those.
Once a slum lord, always a slum lord. He bankrupt a casino, he is not smart. He doesn't understand the difference between a million and a billion; most successful building developers are working in 10 decimal places, Donald isn't even close to that level.