Rep. Stephanie Herseth Sandlin’s campaign is challenging a recent mailer Republican nominee Kristi Noem sent out touting her credentials on Second Amendment rights.

Noem’s mailer cites the South Dakota Democrat’s “D” rating from the gun lobby group Gun Owners of America. It also says that Herseth Sandlin voted for Speaker Nancy Pelosi (D-Calif.) and depicts the National Rifle Association logo with an “F” rating, which is what Pelosi got. The mailer also lists Noem as receiving an “A” rating from the NRA.

What isn’t apparent on the mailer is that the NRA has endorsed Herseth Sandlin.

“Noem is willfully misleading South Dakota voters, and that’s just wrong,” Betsy Hart, deputy campaign manager for Herseth Sandlin, said in a statement. “The NRA endorsed Stephanie in this race because of her proven commitment to protecting our Second Amendment rights.”

Both candidates are appealing to gun owners for votes. The NRA endorsed Herseth Sandlin in late September, also giving her an “A” rating.

Chris Cox, who heads the NRA Political Victory Fund, said at the time of the endorsement that Herseth Sandlin “defended the Second Amendment freedoms of law-abiding gun owners, hunters and sportsmen in South Dakota and across America.”

The NRA has also supported Herseth Sandlin financially. The group contributed $2,500 in the primary and $4,950 in the general election toward her re-election.

“The one thing that is clear to our members in South Dakota is that we did endorse Stephanie Herseth Sandlin,” NRA spokesman Andrew Arulanandam said. “It’s unfortunate that there are efforts to try to insinuate otherwise.”

Noem spokesman Josh Shields is continuing to stand by the mailer.

“We don’t say anywhere in the mailer that we’ve been endorsed by the NRA,” Shield said. “We wanted to make sure that South Dakota gun owners were aware of the fact that Congresswoman Herseth Sandlin supported Nancy Pelosi, who is the most anti-gun Speaker in the history of the U.S.”