Python equivalent would be something like
payload = 'username=myusername&password=password'
headers = {'Content-Type': 'application/x-www-form-urlencoded'}
resp = requests.post('myurl', data=payload, cert=('client-2048.crt', 'client-2048.key'), headers=headers)
payload = 'username=myusername&password=password'
headers = {'Content-Type': 'application/x-www-form-urlencoded'}
resp = requests.post('myurl', data=payload, cert=('client-2048.crt', 'client-2048.key'), headers=headers)