TOPEKA, Kan. (AP) — Former Republican presidential candidate Mike Huckabee has endorsed Kansas Sen. Pat Roberts as he battles an aggressive GOP primary challenge from tea party candidate Milton Wolf.

Huckabee announced his endorsement Thursday. He described Roberts as a conservative warrior and said he’s fought tirelessly for lower taxes and federal government spending.

Huckabee is a former Arkansas governor who now has a talk show on cable’s Fox News Channel. He ran unsuccessfully for the Republican presidential nomination in 2008 but won Kansas’ caucuses.

Roberts is seeking his fourth, six-year term. Wolf is a Leawood radiologist and has the backing of national tea party groups ahead of the state’s Aug. 5 primary.

Wolf spokesman Ben Hartman said Roberts won’t stop his slide in the polls no matter how many endorsements he receives.