They want more than to subvert the American system of government by institutionalizing election fraud and packing the Supreme Court. They want to eradicate the American nation by displacing its people.
“Replacement theory” is not so much theory as observable fact. Leftists, prominently including Joe Biden, have extolled their strategy of achieving a permanent Democrat majority by importing massive numbers of nonwhites from the Third World. This is why no effort is made to resolve the crisis at the border, which could easily be accomplished simply by closing it. It also provides insight into why Biden’s spending blowouts (both the “coronavirus” and “infrastructure” looting sprees) include cash incentives for single mothers who can’t afford to raise them to have more children.
If you doubt the importance of replacement strategy to leftists, behold their reaction if you draw attention to it. Tucker Carlson recently discussed Democrats’ replacement strategy in strictly nonracial terms, yet it triggered vehement denunciations of his alleged racism. Mark Dice thinks leftists will be able to use this to drive him off Fox News:
Things will not go well for Caucasians when leftists achieve their white minority holy grail. The USA will follow South Africa on the road to Zimbabwe.
The Merriam-Webster definition of genocide warrants repetition:
the deliberate and systematic destruction of a racial, political, or cultural group
Leftists will try to silence anyone who draws attention to this objective.
A poll has revealed that in a second-round run-off of the 2022 French presidential elections, populist candidate Marine 
