Senate lawmakers and even the Defense Department have picked a fight with a group they usually go out of their way not to offend: the nation's veterans.

The American Legion and the Veterans of Foreign Wars have come out strong against a Senate bill that would make veterans preference in federal job hiring a one-time benefit, meaning the veteran gets to use it once and that's it.

The Legion slammed the change in the harshest terms, accusing the Defense Department -- which included the change in the National Defense Authorization Act -- of betraying the men and women who had served in uniform.

Related: Veterans Preference Points

"One would think the agency that produces veterans and service-disabled veterans would have the additional moral obligation to uphold the institution of Veterans Preference," Legion National Commander Dale Barnett said in letters to senators and representatives. "Instead, the [DoD] turned their backs on their former employees."

In language less impassioned but no less determined, the VFW released a statement condemning the change.

"Veterans preference is a hand up, not a handout, for those who honorably serve our nation in uniform," VFW National Commander John A. Biedrzycki Jr. said.

Under current law, veterans may use the preference in the federal job market whenever they apply for a job or promotion. The argument has long been that the years they spent away in uniform put them at a disadvantage to peers who entered federal service early on.

Supporters of the Senate provision claim that once the veterans are hired, however, they are no longer at a disadvantage. That is disputed by the veterans' organizations.

"Four years of military service plus four years of government service will never equal eight years of government service," Biedrzycki said. "Even after they are hired, veterans will always be behind their peers who didn't serve in uniform."

According to a June 17 report in The Washington Post, a senior Pentagon official went to Sen. John McCain, R-Arizona, asking for the change. The argument made to McCain is that the benefit results in too many qualified non-veterans losing jobs to unqualified veterans.

One source, who spoke to Military.com on background about the provision, said the Pentagon is finding it difficult to bring in some specialists and even management people because a highly skilled and experienced person and a veteran with several years' experience will both, on paper, meet the minimal requirements cited in a job posting.

And veterans preference means the job will go to the veteran even though the DoD may really want and need the skills brought to the table by the non-vet, the source told Military.com.

This is not the first time that veterans preference has been threatened.

In 2014, the Merit Systems Protection Board released a report claiming that veterans preference was spurring resentment among non-veterans in the federal workforce and also decreased job opportunities for women applying for jobs.

"To any civilian workers who have problems with veterans preference, The American Legion's message is simple: Become a veteran," said the Legion's then-national commander, Michael Helm. "Those who have served in uniform have earned such preference."

Helm also pointed out that there are now more female veterans who could be hired.

-- Bryant Jordan can be reached at Bryant.jordan@military.com. Follow him on Twitter at@BryantJordan.