DOVER, Del. (AP) — Christine O'Donnell has picked up key endorsements from the National Rifle Association and conservative Republican Sen. Jim DeMint of South Carolina in Delaware's Republican U.S. Senate primary.

The NRA said Friday that it can depend on O'Donnell to defend the right to bear arms. The group is asking Delaware gun owners to vote for O'Donnell in Tuesday's primary.

O'Donnell is challenging longtime Republican U.S. Rep. Michael Castle, who has received a grade of "F'' from the NRA for his views on gun–related legislation.

The Tea Party Express, which backs O'Donnell, announced that DeMint, chairman of the Senate Conservatives Fund, has endorsed O'Donnell.

DeMint said on Twitter that O'Donnell "will stand strong for the principles of freedom." DeMint's office confirmed the endorsement.