The biggest thing pushing against CBDC's in general are the commercial banks.
Long term, there is no reason for commercial banks to exist in a CBDC environment, as every user just has direct account with Fed.
Now to add even more to the political complexity, the Fed itself is just a holding company ultimately owned by commercial banks.
Therefore, even if select members of the Fed / Congress thinks they are a good idea, its going to be very difficult to navigate how to implement all of this -- and deal with the fallout.
Lastly, in the US at least, its not clear to me what new benefit they gain that they can't already accomplish in other traditional ways. We already are a 'managed economy' - its not clear that the hassles are worth the benefits.