Problems using random.choice in a while loop

I’m trying to write a program that models the Prisoner’s Dilemma (for my own research purposes), and I’m having trouble generating a random computer choice for every round of the game. Here is my current while loop:

user_points = 0
N_points = 0
games_played = 0

while games_played != games:
    print("Games played: ",games_played)
    s = choice(["confess","remain silent"])
    choice = input("Do you choose to confess to the crime or to remain silent? ")

    if choice.lower() == "confess" or choice.lower() == "remain silent":
        print("You chose to %s, and N chose to %s." % (choice,s))

    else:
        print("Please choose to either confess or remain silent.")


    if choice.lower() == "confess" and s == "confess":
        print("You have both confessed. You both get 9 years in prison.")
        user_points -= 2
        N_points -= 2

    elif choice.lower() == "confess" and s == "remain silent":
        print("You confessed while N remained silent. You walk free while N 
spends the next 7 years in jail.")
        N_points -= 4

    elif choice.lower() == "remain silent" and s == "remain silent":
        print("Fine then...Neither of you wants to talk, but you both still 
get a year each for weapons charges.")
        user_points += 1
        N_points += 1

    elif choice.lower() == "remain silent" and s == "confess":
        print("You remained silent, but N confessed. You'll spend the next 7 
years in jail while N walks free.")
        user_points -= 4

    games_played += 1
    print("Your score is %s." % (user_points))
    print("N's score is %s." % (N_points))
else:
    print("Final Score: You scored %s points. N scored %s points." % (user_points,N_points))
    if user_points > N_points:
        return "Congrats! You have won the Prisoner's Dilemma."
    elif user_points == N_points:
        return "You and N tied. Neither of you wins the Prisoner's Dilemma."
    else:
        return "You have lost the Prisoner's Dilemma."

When I run the code, I get the following error:

Traceback (most recent call last):
  File "<pyshell#10>", line 1, in <module>
    prisonerDilemma()
  File "/Users/stephenantonoplis/Documents/prisonersdilemma.py", line 167, in prisonerDilemma
    s = choice(["confess","remain silent"])
TypeError: 'str' object is not callable

Does anyone know how I might fix this problem? I could define s outside of the while loop, but then the computer would use the same option for every round, which is not random.