https://accounts.google.com/signin/v2/identifier?continue=https%3A%2Fcalendar.google.com%2Fcalendar%2Frender&followup=https%3A%2Fcalendar.google.com%2Fcalendar%2Frender&hd=tmopartners.com&service=cl&sacu=1&rip=1&flowName=GlifWebSignIn&flowEntry=Serv

This URL has not been tested yet.