if statement not working

[trent101010]

I tried this:

#Math God
#By Trenton Varnadoe
#Made in 2018
#You answer questions correctly in under a minute. Each correct answer is worth 50 points. Get one wrong and you get a strike. Three strikes and the game ends. There are three subjects: quadratics, interest, and order of ops. Each contain 50 questions selected at random within that subject.
import time
print("Welcome to Math God! Made by Trent Varnadoe in 2018!")
print("In this game, you have a minute to answer the math problem correctly. If you get it wrong or run out of time, you get a strike. Three strikes and the game is over.")
while True:
	mode = str(input("There are three modes to this game: quadratic, interest, and order of operations. Type 'q' for quadratics, 'i' for interest, and 'o' for order of ops."))
	try:
		if mode = 'p':
  			print("You have selected quadratics.")
		elif mode == 'i':
  			print("You have selected interest.")
		elif mode == 'o':
  			print("You have selected order of operations.")
  	except:
  		input("Sorry, but you didn't correctly choose a valid mode. Press any key to continue.")

and this is what I got:

PauseError: Bad input on line 11.

Any idea on what I'm doing wrong?