variables in complex sql queury/rule

I want to insert values into a view, which is over multiple tables. I use Postgresql.

My solution is to write a rule which inserts all the data into the right table and adds the foreign keys into the rows.

My question is: Can I somehow declare variables into the rule for recurring select-statements?

The code for the rule is:

create rule insert_new_user as on insert to "collHBRS".loginview do instead(
    -- add email_address to email table
    insert into "collHBRS".email(email_addr)     values (new.login_name);
    -- add new empty profile to profile table
    insert into "collHBRS".profile(profile_email_fk, profile_address_fk, profile_student_fk, profile_company_fk)
    VALUES (
            (select email_id from "collHBRS".email where email_addr = new.login_name), -- get email_fk
            null,null,null);
    -- create new login
    insert into "collHBRS".login(login_email_fk, login_password, login_salt, last_login, login_profile_fk)
    values (
            (select email_id from "collHBRS".email where email_addr = new.login_name), -- get email_fk
            new.login_password,new.login_salt,now(),
            (select profile_id from "collHBRS".profile where profile_email_fk =
                (select email_id from "collHBRS".email where email_addr = new.login_name) -- get profile_fk with email_fk
            )
    )
); 

I repeat the select-statement to get the primary key from my new email entry like 2 times.

(select email_id from "collHBRS".email where email_addr = new.login_name) 

I tried it, with DECLARE and WITH AS.

The rule works, it is just not pretty.

Thank you