Congress will return to Washington after Labor Day to some unfinished business, including completing the negotiations on this year's defense policy bill and figuring out a way to move forward a stalled spending bill for the Pentagon.

Lawmakers may have spent the better part of the summer away from Washington, but staffers have been working hard to sort through some of the smaller differences between the House and Senate defense policy bills.

Before leaving for a lengthy summer recess campaigning in home states, lawmakers in the House and Senate officially voted to begin conference on the fiscal 2017 National Defense Authorization Act, saying that staff would be working in their absence on reconciling differences between the two bills

Justin Johnson, an analyst with the Heritage Foundation, said he expects that staff have been working on things that weren't significant debates — essentially anything that didn't make headlines. Some examples include smaller details on acquisition and Goldwater Nichols reform, while the big picture decisions will be negotiated by lawmakers themselves.

While staff are dealing with these smaller discrepancies, some of the bigger fights like Guantanamo Bay transfer restrictions and women in the draft will likely be ironed out by the big four: Sens. John McCain and Jack Reed, Reps. Mac Thornberry and Adam Smith.

The committees did not respond to a request for comment about how often staff had been meeting during the break, or what issues they had been tackling.

Johnson said issues are sorted out through a bottom-up approach. Individual staffers deal with what issues they can, sending unresolved issues up to subcommittee staff leads. The process continues up the food chain, to committee staff leads, then to the lawmakers.

Congress will return after Labor Day not only having to finish up conference on the defense policy bill, but also finding a way to move a defense appropriations bill that stalled in the Senate.

Johnson, however, said he doesn't expect the spending bill to move forward before the beginning of the next fiscal year, since Democrats seem unwilling to budget in their commitment to secure more nondefense spending to match increases in defense.

That means the Pentagon will likely begin the fiscal year on a continuing resolution, which locks in funding as last year's level and prevents the start of new programs.

"That's going to be a big albatross hanging around the department's neck probably through November or December. That's unfortunate, but it's not really new," he said.