With Pentagon officials making their way to Capitol Hill in recent days, the contours of congressional debate over the President’s fiscal year 2016 budget request are starting to take a shape. The defining feature of that debate will be within the Republican Party as fiscal hawks square off against defense hawks. As of right now, the latter are in the minority, but knowing that, they are coming out swinging.

The Republican chairs of Senate and House Armed Services Committee, John McCain and Mac Thornberry for all intents and purposes lead the defense hawk side of the debate—with the former receiving ample support from Senator Jack Reed of Rhode Island, the ranking Democrat on the Senate side. Both committee chairmen sent their “views-and-estimates” on the defense budget to each chamber’s budget committee over the course of the past week. In his letter, Thornberry asked for $566 billion in base funding for the Pentagon. McCain, for his part, asked for $577 billion.

The aggressive requests from McCain and Thornberry were likely a response to indications that the chairman of the House Budget Committee, Republican Representative Tom Price, planned to pass a budget resolution in line with the Budget Control Act spending limits. While no official word has come out of the Senate Budget Committee, analysts believe that Republican Senator Mike Enzi, chairman of the committee, is content to maintain the budget cap. Moreover, Vermont Independent Senator Bernie Sanders, ranking member on the committee, recently wrote to Secretary of Defense Ashton Carter requesting a meeting on waste at the Pentagon.

Given that they chair authorizing, not appropriating committees, McCain and Thornberry will have to make their case for increasing the defense budget to Enzi and Price, as well as to the appropriations committees. At least on the House side, that looks to be an uphill battle. As Jeremy Herb of Politico Pro Defense reported this morning, while Secretary Carter faced a sympathetic audience appearing before McCain’s committee recently, his appearance before the House appropriators yesterday was more adversarial. While New Jersey Republican Representative Randy Frelinghuysen, chair of the Defense Appropriations Subcommittee, said he wished Budget Control Act limits could be lifted, he also acknowledged the spending caps are the law of the land and the committee would remain faithful to them. Frelinghuysen already warned U.S. Navy and Marine Corps’ leaders that they needed to begin thinking about where they will make cuts to get under the cap on national defense.

So where does that leave things moving forward?

In a conversation with Defense One, former Department of Defense Comptroller Robert Hale laid out three scenarios. In one, Congress appropriates an amount at or near the level requested by the Obama administration—thus triggering the across-the-board cuts defense officials and congressional hawks continually warn against. In a second scenario, a deal to temporarily raise the spending caps as the Ryan-Murray deal did in 2013 is reached. Hale and others do not see that as likely at the moment given the lack of an existing framework for negotiations. In the final scenario, the one Hale finds most likely, funds are appropriated in line with the Budget Control Act limits—meaning Congress would decide what was to be cut from budget request. Such a scenario is all the more reason the Pentagon officials need to get their own house in order as they continue to plan for FY 2017.