SELECT .. INTO to create a table in PL/pgSQL

Try

CREATE TEMP TABLE mytable AS
SELECT *
FROM orig_table;

Per http://www.postgresql.org/docs/current/static/sql-selectinto.html

CREATE TABLE AS is functionally similar to SELECT INTO. CREATE TABLE AS is the recommended syntax, since this form of SELECT INTO is not available in ECPG or PL/pgSQL, because they interpret the INTO clause differently. Furthermore, CREATE TABLE AS offers a superset of the functionality provided by SELECT INTO.