To convince Greens or Carlins (people who don't vote because the Democrats are still too evil from their point-of-view) to vote for Democrats, you need to understand yourself and them. Once you do that, you'll be able to offer more convincing arguments to support your position.
If you're voting for Democrats, you possibly agree with the following scale of evilness:
- 10 Hitler
- 9 Stalin
- 8.5 Trump
- 8 Republicans and people who vote for them
- 7
- 6
- ~5-3 elected Democratic party members
- 2
- 1 you
- 0 Jesus
The thing is that Greens and Carlins see the world very differently:
- 10 people making the biosphere unlivable thru overpopulation
- 9 factory farmers and commercial fishing companies
- 8
- 7 Hitler, Stalin
- 6
- 5 George W. Bush, Putin
- 4 Trump, Republicans, and people who vote for them
- 3 Gore, Obama, Democrats, and people who vote for them
- 2
- 1 Sanders
- 0
- -1
- -2
- -3
- -4
- -5
- -6
- -7 them
- -8
- -9
- -10
The Greens' and Carlins' priorities are very different. They may think that choosing to make the biosphere unlivable is the worst thing you can do, because without a biosphere that supports life, nothing else matters.
They may think that torturing trillions of fish to death every year, and enslaving hundreds of billions of animals in torturous conditions every year, is worse than all genocides and wars in all of history combined. They think that supporting even a single genocide is bad.
They may think that given the choice between popular Hitler, popular Stalin, and unpopular Gandhi; they'd rather vote for Gandhi than the popular lesser evil, because that specific evil is omnicidally evil. It's better to vote for good and fail, than it is to vote for evil and succeed.