Bill O'Reilly welcomed back "Daily Show" host Jon Stewart to "The Factor" tonight, pressing him on why the Democrats lost so badly in the midterm election. 

Stewart said Democrats didn't run on anything, choosing to "curl up in a little ball" and try to make the argument that they also disagree with President Obama. 

"Here's what they ran on: 'we don't like Obama either. I don't know who voted for him. We don't want anything to do with the guy,'" said Stewart. 

O'Reilly argued their strategy stemmed from the fact that Obama's approval ratings had declined so dramatically.

Stewart then said he believes there's a disconnect between President Obama and Democrats, which did not exist when Bill Clinton was in office. 

"I believe he has a bit of disdain for the Democrats, I believe they have a bit of disdain for him. It's not like the Clinton machine," said Stewart. 

O'Reilly countered that Democrats lost because young voters, Stewart's viewers, did not show up at the polls.

He drew a laugh from Stewart when he joked that marijuana is now legal in so many states, "there's no incentive for them to leave the house."

Stewart called out Republicans for getting together in 2009, and agreeing that they would block Obama's agenda at every turn.

"When he came into office, the Republicans met in a restaurant and said, 'We will deny this man any bipartisan agreement. We will undercut anything that he offers, to the detriment of the country but the short-term gain of our party and that is how they've operated the past six years," said Stewart.

O'Reilly countered that when Democrats had the House and Senate for two years, they chose to focus on ObamaCare and not on immigration reform. 

Stewart said Democrats are to blame as well, but argued the Republicans have gained politically by never "owning" anything and winning by "attrition."

O'Reilly ended by saying that all he's asking on immigration is that any undocumented "Daily Show" viewers be deported. 

Watch the entertaining debate above.

In part two of the discussion (below), Stewart delved into his new film "Rosewater," which tells the story of a journalist jailed in Iran while covering the disputed 2009 election.