Leftists believe all opposition to them is based on racism.....or something.
I dont think they necessarily believe it.
Calling political adversaries racists, etc. is a favorite weapon of the Left, and with the aid of their propaganda ministry, the MSM, they know their lies will go unchallenged.
They arent stupid enough to believe that open borders are actually a good thing, or that transsexual men belong in the girls bathroom, or that climate change will destroy the planet in 12 years, or that President Trump is a white supremacist, or any of the other rubbish they promote - they simply want to discredit their Republican opponents by any means whatsoever.
As soon as there is another Democrat in the Oval Office, they will change gears - it was OK for Obama to deport 3 million illegals and put detainees in cages - and it will be OK for the next Democrat President.
They lie all the time. Who knows what they really believe about anything.