alter column from time with time zone to timestamp

alter column from time with time zone to timestamp

I am having trouble changing a column called end_date in a table called
key_request from time with time zone to timestamp in my Postgres database
. I have tried using the following code:
alter table key_request alter column end_date type timestamp with time
zone using end_date::timestamp with time zone
I keep getting the following error:
ERROR: cannot cast type time with time zone to timestamp with time zone
Any idea of how I can adjust this query to work?