Neil Abercrombie said a letter sent from D.C. was "far from being a dying wish."
The numbers are the latest sign that Pryor hasn't withered under a deluge of attacks.
West Virginia's secretary of State nearly paced Rep. Shelley Moore Capito in fundraising.
The haul is an increase from the $1.6 million she raised last quarter.
"Mitch McConnell is a true champion of our Second Amendment rights," the group said.
Organizing for Action said it raised about $5.9 million in the first three months of 2014.
That's a huge jump from 2012, when the group raised just $1.7 million in the first quarter.
The former VP nominee calls the Ga. Senate hopeful a "conservative who has walked the walk."
"Starting today, I am a candidate for the United States Senate," he said at a rally.
The new effort comes the same day the former Massachusetts senator officially launches his campaign against New Hampshire Sen. Jeanne Shaheen (D).