WASHINGTON — Troops saw lawmakers approve their biggest pay raise in a decade in 2018. And the next boost could be even bigger than that.

Continuing a trend in recent years, the pay raise for 2020 is expected to again rise thanks to the improving economy and the expected increase in civilian sector wages. Based on the current federal formula, troops should see a 3.1 percent pay raise in January 2020, up 0.5 percent from the 2.6 percent raise that goes into effect this January.

If that holds, it would mark the fifth year that troops saw a bigger pay raise than the previous year. But actually getting the money depends on Congress and the White House.

President Donald Trump has signaled support for maintaining strong military pay, but he has also discussed trimming the total Defense Department budget by tens of billions of dollars to help reduce the federal deficit.

Pentagon planners could reduce their spending plans without touching the annual pay raise, but the salary increases have been an easy target for savings because of the large effects even small changes can make.

Dropping the pay raise by 0.5 percent — which leaves troops with a large paycheck but not necessarily one that keeps up with civilian wages — can save up to $3 billion over five years for the Defense Department.

But military advocates have long argued that such moves undermine promises to provide for troops and their families.

In a message to members earlier this year, Military Officers Association of America Vice President Dan Merry noted that military pay raises were capped at lower-than-civilian rates in the mid-2000s, with problematic results.

“Any decision to cap military pay kicks off a slippery slope,” he said. “Once pay is capped one year, it's easy to do it again and again. Decisions to make small caps to military pay raises over time eventually resulted in a 13.5 percent pay raise gap, leading to dismal recruiting and retention.”

“We expect a lot from our troops. Let's pay them what they deserve.”

The White House’s formal Defense Department appropriations request is scheduled to be unveiled in February. After that, expect months of wrangling over the totals and details, with the pay raise target at the center of the debate.