Though it's an unsurprising endorsement for the candidate, who has received an A grade from the group for his support of Second Amendment rights in comparison to Sen. Claire McCaskillClaire Conner McCaskillNSA spying program overcomes key Senate hurdle Senate campaign fundraising reports roll in Dems search for winning playbook MORE's (D) F grade, it's significant for being another national group unafraid to come out in support of the embattled congressman.

Akin cited the NRA endorsement and his endorsement from the Missouri Farm Bureau as evidence that his "record is in step with most Missourians," compared to McCaskill, who he called "a liberal's liberal."

"McCaskill's record would fit better in California or New York than in Missouri," he said in a statement.

Though Akin lost the backing of his party establishment when he refused to exit the race following controversial comments he made about rape, he's begun to receive a slow trickle of prominent endorsements since the deadline for him to drop out has passed.

Former GOP presidential candidates Newt Gingrich and Rick Santorum have endorsed him in recent weeks, and Sen. Jim DeMint's (R-S.C.) Senate Conservatives Fund invested $300,000 into the race.