The National Rifle Association has endorsed Kansas Gov. Jeff Colyer in his Republican primary race against a field that includes Secretary of State Kris Kobach.

But Kobach touted his own endorsement Monday by Gun Owners of America. The group describes itself as a "no-compromise" gun-rights organization.

Colyer released a copy of a letter Monday from the NRA's political action committee backing Colyer and giving him an "A'' rating.

The letter became public shortly after Kobach announced his endorsement.

The Kobach camp claimed Colyer only got the endorsement because the organization has a rule designed to protect incumbents. The campaign also pointed to a Kansas Rifle Association poll in which Kobach took the support of 57% of its members, topping Ken Selzer's 35%, and 50 points ahead of Colyer.

Colyer and Kobach have both portrayed themselves in their Aug. 7 primary race as strong supporters of gun rights. Gun-rights advocates are a key part of the Kansas GOP's base.

Kobach rides in parades in a jeep painted with a U.S. flag design with a replica machine gun on back.

Gov. Scott Walker endorses Colyer

Wisconsin Gov. Scott Walker also endorsed Kansas Gov. Jeff Colyer as Colyer faces a crowded Republican primary featuring a serious challenge on his right.

Walker said in a statement that he is backing Colyer in his bid to stay in office because Colyer has shown "real commonsense, conservative leadership."

"I'm glad to endorse Jeff Colyer because I know he’ll stand up for hard-working families to get things done," Walker said.

Walker is among the nation's most prominent Republican governors and is seeking a third term in Wisconsin.

"Scott Walker has been at the forefront of the fight for conservative values for years, both in Wisconsin and on the national stage," Colyer said. "I am thrilled to have the endorsement of one of America's most capable and effective conservative leaders."

Colyer's opponents in the contentious Aug. 7 primary race include conservative firebrand and Secretary of State Kris Kobach.

Kobach spokeswoman Danedri Herbert responded to Walker's action with an email saying, "So what? Who cares what some guy from Wisconsin thinks?"

Walker's endorsement of Colyer came a day before a planned Kobach fundraiser in Wichita with Donald Trump Jr.