Conservative activist and media leader Andrew Breitbart died early on Thursday from natural causes at age 43, according to an announcement on his website.
(PICTURES: Notable Deaths of 2012)
In their eulogy, Big Journalism writes, “Andrew lived boldly, so that we more timid souls would dare to live freely and fully, and fight for the fragile liberty he showed us how to love.”
Breitbart was often at the center of conservative media causes, including attacks on Media Matters, ACORN and the resignation of Shirley Sherrod in 2010.
Campaigning in Dalton, Ga., Republican presidential contender Rick Santorum said he was "crestfallen, that's horrible."
"Obviously prayers go to him and his family and wow, its a big shock. What a powerful force. Its almost - you think of anybody out there who's just more energy, and just, out there constantly, driving and pushing. What a huge loss, in my opinion for our country, and certainly for the conservative movement," Santorum said.
Republican rival Mitt Romney tweeted: "Ann and I are deeply saddened by the passing of @AndrewBreitbart: brilliant entrepreneur, fearless conservative, loving husband and father."