House Majority Leader Eric Cantor suffered a bruising primary defeat by tea party challenger Dave Brat on June 10.

Strategists say Cantor’s 11 percentage point loss was due to a lack of field effort, fueled by overconfidence in his path to victory. Many Republicans felt Cantor had become too removed from his district, mired in Washington infighting and too focused on the national stage.

According to historians, no House leader of Cantor’s rank has ever been defeated in a primary.