Negotiate Authentication Scheme in a POST Request

I'm using the requests library to request a URL, but the site requires authentication. I've tried using the basic authentication, there is an error when using just urllib saying the scheme is "Negotiate," and I get a 401 error when I try with requests. Using urllib3.contrib.ntlmpool doesn't work because Lambda can't find the "ntml" library that ntlmpool tries to import from. Is there a way to do this with the libraries available through AWS or must I use another library?