You can try to use Create Table As command like this:
CREATE TEMP TABLE mytable AS
SELECT * from source_tab;
From the docs:
This command is functionally similar to SELECT INTO, but it is preferred since it is less likely to be confused with other uses of
the SELECT INTO syntax. Furthermore, CREATE TABLE AS offers a superset
of the functionality offered by SELECT INTO.
The CREATE TABLE AS command allows the user to explicitly specify
whether OIDs should be included. If the presence of OIDs is not
explicitly specified, the default_with_oids configuration variable is
used.
