import tkinter as tk
root = tk.Tk()
rbvar = StringVar()
rbvar.set(" ")
rb1 = tk.Radiobutton(root, text="Option 1", variable=rbvar, value='a', indicatoron=0)
rb1.pack()
rb2 = tk.Radiobutton(root, text="Option 2", variable=rbvar, value='b', indicatoron=0)
rb2.pack()