Gov. Mike Dunleavy, R-Alaska, announced Thursday he is joining a lawsuit Gov. Gregg Abbott, R-Texas, filed earlier this month against the Biden administration challenging vaccine mandates for the National Guard.

The complaint, filed in Texas federal court, argues that President Biden's federal vaccine mandate is unconstitutional and undermines state sovereignty as well as the authority of state governors over National Guard units.

"This is not a case demanding a position of pro- or anti-vaccine, nor is it a case that challenges any aspect of the federal government’s authority over National Guardsmen once that federal authority has been properly established," the complaint states.

"Instead, this case seeks to have federal action combined within federal authority, prohibiting the federal government’s unconstitutional attempt to force Texas and Alaska, through their governors, to submit to federal orders and impose federally dictated disciplinary action on their National Guardsmen."

Federal vaccine mandates for members of the National Guard have proven contentious, since Title 32 of the U.S. code places the National Guard under the authority of state governors, while Title 10 puts them under federal control if the president calls them up.

"Protecting the freedom and liberty of National Guard members has fallen on responsible governors," Dunleavy said in a statement. "The federal government has no authority to make health decisions for National Guard members who are at work under state authority. I pledge to protect that medical freedom and to challenge the trampling of our state’s rights under the 10th Amendment."

In December, a federal judge rejected a similar lawsuit from Gov. Kevin Stitt, R-Okla., who likewise sued to block the federal vaccine mandate for his state's National Guard.

FILE - In this Sept. 27, 2019, file photo, Alaska Gov. Mike Dunleavy speaks at a news conference in Anchorage, Alaska. Dunleavy on Tuesday, March 9, 2021, announced that the COVID-19 vaccine is available for all individuals who live or work in Alaska and are age 16 and older, making Alaska the first state in the nation to remove eligibility requirements. (AP Photo/Mark Thiessen)

In this Sept. 27, 2019, file photo, Gov. Mike Dunleavy, R-Alaska, speaks at a news conference in Anchorage.  (AP Photo/Mark Thiessen)

TEXAS GOV. ABBOTT TO SUE BIDEN ADMIN OVER VACCINE MANDATE FOR NATIONAL GUARD

Along with Gov. Mark Gordon of Wyoming, Gov. Kim Reynolds of Iowa, Gov. Tate Reeves of Mississippi and Gov. Pete Ricketts of Nebraska, Dunleavy and Abbott were among the five governors who sent a letter to the Pentagon in December asking it to rescind the order.

Secretary of Defense Lloyd Austin on Aug. 25 directed all branches of the military to ensure service members receive the vaccine as case numbers surged over the summer, though the deadlines vary depending on the branch. The Army National Guard has until June 30 to get vaccinated.

Texas Gov. Greg Abbott

In this March 16, 2020, file photo, Texas Gov. Greg Abbott speaks during a news conference in San Antonio.  (AP Photo/Eric Gay, File)

On Jan. 4, Abbott sent a letter addressed to Maj. Gen. Tracy Norris, adjutant general of the Texas Military Department, explaining why he was suing the federal government.

CLICK HERE TO GET THE FOX NEWS APP

"Let me be crystal clear: It is the federal government that has put Texas’s guardsmen in this difficult position. As your commander-in-chief, I will fight on your behalf. That is why I am suing the Biden Administration over its latest unconstitutional vaccine mandate," Abbott wrote in part.

The Pentagon did not immediately respond to a request for comment.