how to use delegate_to with Ansible tower

[Neetu]

Hi,

I have a task which I am delegating to a different host .

Playbook is running on dev host, and the task is being delegated to qa host to run. 

- name: "Delegate to qa"

    shell: " task "

    delegate_to: "{{ qa_host }}" 

    become_user: "{{ qa_user }}"

If I run it from my local terminal, it works. How ever from tower it fails because of 'permission denied'.

Machine credentials for dev are passed to the playbook during run time. Is there a way we can send the credentials for qa host in tower ?

Thanks,

Neetu