The Republican Party's right wing is threatening to derail passage of the National Defense Authorization Act of 2015, worth around $580 billion, over the inclusion in the military budget of what a prominent conservative commentator called "liberal pet projects" that have little to do with defense.

At stake is a series of provisions allowing the U.S. government to expand federal land holdings. While the provisions seem harmless -- calling for new national parks, a women’s history museum and up to 275,000 acres in designated wilderness areas --conservatives say the defense bill is no place to fund them. 

According to a Democratic summary of the act provided to CQ Roll Call, the legislation “is vital to our national security and provides our men and women in uniform with the tools they need as well as the benefits and support that they have earned and deserve.”   

"The decision to attach an extreme land grab to the NDAA is a disservice to members of the armed forces," wrote Sen. Ted Cruz, R-Texas, on his website. "With the military's shrinking budget, it is offensive that this bill would be used to fund congressional pork. And, at a time where jobs are scarce and the federal government has removed billions of acres of land from productive use, Congress should not be restricting more than a half-million new acres."

He added: "The House and Senate should reject this attempt by self-serving politicians to exploit the men and women of the military to serve their special interests."

Under "TITLE XXX—NATURAL RESOURCES RELATED GENERAL PROVISIONS," the 2015 bill provides for a number of actions on federally managed lands. Those include extensions at 16 National Heritage sites, new Wild and Scenic River designations, additions to National Historical Parks, setting aside of lands in several Western states, and even the creation of a commission to study building a Women’s History Museum.  

By current figures, the Department of Interior manages around 640 million acres of land, with a $20 billion budget.

Gaston Mooney, executive editor of Conservative Review, said "proponents of this land grab are trying to conceal the legislative language amongst other must-pass legislation that is critical for our national security. Jamming liberal pet projects into a defense bill at the expense of American’s best and bravest is something you’d expect from the Left."

Dan Caldwell, the legislative director for Concerned Veterans of America, said the provisions were “disgraceful” while troops see rising health care and housing costs. “Congress has refused to adequately address other long-term issues with the defense budget --including the threat of sequestration and the broken acquisition system which wastes billions of dollars while failing to deliver much-needed equipment to our war fighters,” he said in an interview with conservative site Breitbart News.