The Democrat party has become so radical and unpopular that the only way it can consistently win elections is by rigging them.
So it rigs them.
The Democrats are the party of radicalism and election rigging.
Since COVID, we have instituted a system of legalized election theft in this country that defies both the conspiracy theories of the right and the protestations of the left. That’s because the “theft” is legal. Here’s a good description of how the system works in California.