Sen. Bernie Sanders and former Sen. Rick Santorum disagree on just about everything when it comes it politics. But the two also each have big differences with their parties' establishment.

Santorum is at odds with Gov. Chris Christie & others in the Republican party, arguing they need to elect an apologetic conservative, not a moderate candidate. After saying that winning the White House "...may be a win for the Republican candidate but it will be a devastating loss for America," Christie hit back, saying "we don't get to govern if we don't win."

Meanwhile, Sanders tells The Nation that leadership needs to explain to the American people why they are hurting and how to grow the middle class, but doesn't think "that is the politics of Senator Clinton or the democratic establishment."

Sanders and Santorum will face in the Crossfire, joined by S.E. Cupp and guest host Marc Lamont Hill.

We want you to weigh in: If Hillary Clinton runs, will she get a significant primary challenge on the left?

Vote by tweeting Yes or No using #Crossfire or by commenting on our Facebook post. View results below or through our Poptip results page.