WASHINGTON — Two of the US Senate's old bulls squared off on the chamber floor Thursday morning, trading barbs over the fate of a Pentagon policy bill.

Sens. John McCain, R-Ariz., and Harry Reid, D-Nev., were part of the freshman class that took office on Jan. 3, 1987. Over their 28-year stints in the upper chamber, the two have done battle many times.

Now, the Senate Armed Services Committee chairman and minority leader are leading a partisan squabble over McCain's 2016 National Defense Authorization Act (NDAA).

The SASC chairman's annual Pentagon policy bill includes an $88.4 billion overseas contingency operations (OCO) account. McCain grudgingly accepted GOP leaders' decision to add $38 billion in essentially base-budget dollars to the war fund, concluding it was the only way to get the military more funding to offset spending caps.

Reid and other congressional Democrats call the move a "gimmick." They also want more funding for domestic programs.

President Barack Obama also opposes the move and wants domestic spending hikes, saying he would veto any measure that adheres to spending caps or gives DoD more funding without assurances of the same for domestic programs.

As the chamber moved to the Pentagon bill, Reid almost immediately called the work "a waste of time" because Obama's veto awaits. The drama continued Thursday morning as the Senate came into session.

"The bill before us is designed to write an end-run around sequestration for the Department of Defense by exploiting a provision that exempts spending caps called the overseas contingency operations," Reid said. "We all know that OCO was put in the budget many years ago and it was set there so we would have the money to fight wars.

"I'm disappointed that even senators who long have had a reputation for fiscal honesty, like the chairman of the Armed Services Committee, my friend, are turning a blind eye to the OCO gimmick," Reid said. "Not a word about this gimmick."

Reid noted senior Pentagon officials oppose the inflated war fund.

"If any bill reaches the president, he'll veto it. ... He should," Reid said, accusing GOP leaders of "wasting time on a bill that has no chance of becoming law — no chance."

Minutes later, McCain charged Reid with not having his priorities in order.

A fired-up McCain lectured Reid and other Democrats on the definitions of authorization and appropriations legislation.

McCain said an authorization bill "does not fund" specific programs or agencies, but rather gives departments the green light to expend funds.

He urged Reid to "have the fight" over the war funding and the minority leader's call for a solution to the much-loathed capped federal budget during work on appropriations bills.

Security moves people along Rue Bichat following a string of attacks in the French capital Paris on November 13, 2015. At least 18 people were killed as multiple shootings and explosions hit Paris Friday, police said. Police also said there was an ongoing hostage crisis in the Bataclan a concert hall in the French capital. AFP PHOTO / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
Security moves people along Rue Bichat following a string of attacks in the French capital Paris on November 13, 2015. At least 18 people were killed as multiple shootings and explosions hit Paris Friday, police said. Police also said there was an ongoing hostage crisis in the Bataclan a concert hall in the French capital. AFP PHOTO / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)

There was some question all week about whether Obama actually would veto legislation with so many policy prescriptions that would directly affect US military personnel. But Reid's comments on Thursday morning were stronger and more certain than his mention of the veto threat on Tuesday afternoon.

Meantime, the chamber began votes on amendments to the SASC bill by passing one from Sen. Rob Portman, R-Ohio, that would add $371 million to the Army's Stryker vehicle program.

The amendment would move that amount from elsewhere in the budget to fund work identified late this spring by the service to bolster the General Dynamics-made vehicles.

As SASC Ranking Member Sen. Jack Reed, D-R.I., noted on the floor Thursday morning, the Stryker upgrade work would be done in Ohio. It passed 61-34, with the support of GOP and Democratic senators despite Reed's opposition.

Twitter: @bennettjohnt