Fabric: ¿Cómo crear una conexión con contraseña?

Esto es cuando mi clave pública está presente en el servidor:

>>> c = Connection(host=ip, user='root', port=22)
>>> c.run('uname -s')
Linux
<Result cmd='uname -s' exited=0>

Esto es cuando mi clave pública se elimina del servidor:

>>> c = Connection(host=ip, user='root', port=22)
>>> c.run('uname -s')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<decorator-gen-3>", line 2, in run
  File "/usr/local/lib/python2.7/dist-packages/fabric/connection.py", line 23, in opens
    self.open()
  File "/usr/local/lib/python2.7/dist-packages/fabric/connection.py", line 488, in open
    self.client.connect(**kwargs)
  File "/usr/local/lib/python2.7/dist-packages/paramiko/client.py", line 424, in connect
    passphrase,
  File "/usr/local/lib/python2.7/dist-packages/paramiko/client.py", line 691, in _auth
    self._transport.auth_publickey(username, key))
  File "/usr/local/lib/python2.7/dist-packages/paramiko/transport.py", line 1450, in auth_publickey
    return self.auth_handler.wait_for_response(my_event)
  File "/usr/local/lib/python2.7/dist-packages/paramiko/auth_handler.py", line 212, in wait_for_response
    raise e
AttributeError: '_RSAPrivateKey' object has no attribute 'sign'

¿Cómo pasar la contraseña a Connection? PD: no pude encontrarlo en la nueva documentación (2.0).