Store output of subprocess.Popen call in a string [duplicate]

I’m trying to make a system call in Python and store the output to a string that I can manipulate in the Python program.

#!/usr/bin/python
import subprocess
p2 = subprocess.Popen("ntpq -p")

I’ve tried a few things including some of the suggestions here:

Retrieving the output of subprocess.call()

but without any luck.