Unable to switch user using paramiko python

Question

When I login via putty, I give my username and password and login. After logging in, I use the below command to switch to a different user group:

sudo su - test_user

I enter the password when promted and the user changes to test_user.

Now I am trying to achieve the same using python Paramiko. But I am not able to do it. Below is the code that I have tried:

import paramiko

hostname = 'host'
port = '22'
username = 'bs'
password = '*****'

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.load_system_host_keys()
ssh.connect(hostname=hostname, username=username, password=password)

stdin, stdout, stderr = ssh.exec_command('sudo su - test_user')
stdin.write('*****\n')
stdin.flush()
print(f"STDOUT: {stdout.read().decode('utf8')}")
print(f"STDERR: {stderr.read().decode('utf8')}")

ssh.close()

The error I get is:

STDERR: sudo: no tty present and no askpass program specified

I have also tried the below but I still could not switch user:

stdin, stdout, stderr = ssh.exec_command('sudo su - test_user', get_pty = True) -> the code keeps running and does not end until manually stopped.

stdin, stdout, stderr = ssh.exec_command('sudo -S test_user')
Error:
STDERR: [sudo] password for bs: sudo: test_user: command not found 
    
stdin, stdout, stderr = ssh.exec_command('sudo -S chown -R test_user:test_user /tmp/test.txt')
Error:
STDERR: [sudo] password for bs: