regex – Ansible lineinfile regexp line with many spaces

I have a line in a configuration file that I would like to change by removing the comment.
/etc/pam.d/su

#%PAM-1.0
auth            sufficient      pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth           sufficient      pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
#auth           required        pam_wheel.so use_uid
auth            substack        system-auth
auth            include         postlogin
account         sufficient      pam_succeed_if.so uid = 0 use_uid quiet
...

I need to remove the comment only from the line
#auth required pam_wheel.so use_uid

but regexp does not find the string if I write it completely with spaces.

I use the below code:

- name: Modify PAM
  ansible.builtin.lineinfile:
    path: /etc/pam.d/su
    regexp: '^#auth           required        pam_wheel.so use_uid'
    line: 'auth            required        pam_wheel.so use_uid'
    backrefs: true
    backup: true

If I remove backrefs, the line is created below, but I would like to replace the line.