Hi,
It is said here - https://github.com/ansible/ansible - that Ansible uses SSH by default. Is it possible to run Ansible on localhost system without SSH installed?
Yes, use “-c local”.
I wonder if this can be done per play.
Yes
connection: local
As a play setting is the same as local_action on every task, be sure to only select one host in the loop!
– Michael
Thanks! that helped 
I had a machine with 2FA for SSH enabled. I needed to apply my playbook there. SSH into localhost from localhost was also not working for obvious reasons. Had almost given up when I found this! Saved me a considerable amount of manual labour!