Santorum said Sunday "I don't back away from any of those things."
Santorum had also argued in March that Republicans should give President Barack Obama a second term because Romney wasn't conservative enough. The former Pennsylvania senator now says "clearly, the difference between President Obama and Mitt Romney is a chasm."
Should Romney win in November, Santorum says he would advise Romney if asked but not serve in his administration. He said: "It's pretty much a flat no."
Santorum tells CNN'S "State of the Union" that he wouldn't consider working for a Romney administration because his priority lies with his family.
(Copyright 2012 The Associated Press. All rights reserved.)