It's not 2010 anymore.

So far this year, establishment Republicans have been much more successful at defending their Congressional seats from primary challengers, particularly on the far right. It's a serious departure from 2010, when a wave of Tea Party conservative groups rose to prominence across the country.

So what's changed? For starters, incumbents were more prepared for a fight this time around.

In the latest WEX BackStory, Washington Examiner Political Correspondent Rebecca Berg explains how incumbent Republicans are successfully defending their seats against Tea Party challengers during the 2014 primaries.