Advancing a defense authorization bill was as painless this year as it has been in decades, according to the people who wrote the measure.

The House adopted the fiscal 2019 NDAA conference report in a lopsided 359-54 vote on Thursday just before that chamber’s members left town for the August recess.

When the Senate adopts and the president signs the measure in the coming days, as they are expected to do, it will mark 58 years in a row the legislation will have become law.

But getting to yes usually takes longer than it did this year. Only twice in the last 33 years has the measure been enacted prior to the Oct. 1 start of the fiscal year. The most recent time that happened was more than two decades ago, in fiscal 1997. The last time the NDAA was enacted before September was way back in fiscal 1978.

“I was actually in the first grade the last time we passed a defense authorization bill this fast,” House Speaker Paul D. Ryan told reporters this week.

Fixed budget

Normally, some politically charged issue ends up sidetracking the measure for weeks or even months. Not so this year.

The biggest reason things went so smoothly, members and aides said, is that the budget number was not up for negotiation.

Instead, the defense budget cap for the coming fiscal year was established as part of a law enacted in February that revised upward both the defense and nondefense caps for fiscal 2018 and 2019.

Asked how to explain this year’s unusually fast progress on the authorization bill, House Armed Services Chairman Mac Thornberry of Texas, who helped lead the conference, answered: “Two-year budget deal. That’s No. 1. If you know the number you are working to, you can work it out.”

Likewise, Adam Smith of Washington, the top Democrat on the House Armed Services Committee, said in floor remarks Thursday that having a budget agreement “helped a great deal” in greasing the skids for the conferees.

The total amount of money available for defense in fiscal 2019 was not only fixed, it was a lot.

The newly revised budget law permitted spending up to $647 billion for the so-called base budget, meaning everything but war spending, which is not capped by the law. The Armed Services committees’ portion of that base-budget total, the amount reflected in the new authorization conference report, is $639.1 billion.

The authorizers merely endorsed that level of spending. Now congressional appropriators are clearing spending bills that provide the actual budget authority.

On top of the base budget would come $69 billion in war funds.

Subtracting out war costs, the base defense budget for fiscal 2019 will be the most money America has spent on the military since World War II, adjusting for inflation, experts say.

Thornberry said knowing the budget number was more important than the fact that it was so large. But senior aides involved in the process said the size of the budget figure did help in easing or just avoiding disputes.

“If the pie is big, everybody can get some size of slice,” said one senior staffer.

Of provisions and politics

The conference also moved along briskly because members and aides have learned a hard lesson in recent years, especially election years: The longer it takes to resolve conference disagreements, the closer Election Day comes and the more likely it is for politically explosive issues to be introduced in the process at the behest of the leaders of one or both parties.

The NDAA is not only must-pass legislation, it is always-passes legislation. So it tends to attract riders that are only tangentially related to defense, if at all — issues such as gun control or the environment.

In addition, defense-related disputes also have loomed large in the recent past — such as over major weapons like the F-22 fighter jet program; the future of the U.S. military-run detention center at Guantanamo Bay, Cuba; the role of women or LGBT people in the military; or the rights of alleged terrorists in U.S. detention.

If the bill remains unresolved into the fall, as it typically does, it can be a magnet for debates that the parties think galvanize base supporters.

This year, there were just fewer such controversies in the House and Senate bills, and people were determined to avoid adding any hot-button new topics.

Members and staff shared a “motivation to finish before the pressure grew to add midterm-motivated airdrops,” one senior aide said.

Another reason for the speedy completion of the NDAA conference: the Armed Services Committees undertook fewer major overhauls of Defense Department operations than they have in some years past, such as the sweeping changes proposed previously in the U.S. military’s acquisition, personnel or retirement systems.

The bill did make adjustments to these systems, but they were not the major muscle movements of some years past.

“There were no big efforts to move the building around,” one staffer said, in a reference to the Pentagon.

Presence of the absent McCain

Then there was the effect on the conference of John McCain, the Senate Armed Services chairman. His sway was considerable, even though he is being treated for brain cancer in his home state.

The fiscal 2019 law will be named after the Arizona Republican. Conferees said they wanted to ensure that the bill could be enacted as soon as possible for him. They said they didn’t want to fumble the job in his absence.

“There was a sentiment that you really want to get it done while McCain is still here,” said GOP Rep. Mike D. Rogers of Alabama.

“Maybe people were acting out of respect for his legacy,” said GOP Rep. Doug Lamborn of Colorado.

“We were honored to get it done for McCain,” said Democratic Rep. Jim Langevin of Rhode Island, another senior conferee.

McCain’s views were well-known and communicated to the conferees, according to Thornberry. James M. Inhofe of Oklahoma, the No. 2 Republican on the Senate Armed Services panel, stood in for McCain.

“His stamp is obviously on it very heavily,” Thornberry said. “In the negotiations, Sen. Inhofe was very faithful in advocating for Sen. McCain’s position.” Thornberry added that this position was sometimes “tricky” for Inhofe, “because he might have had different opinions of his own.”