By Kristina Wong - 01/13/15 04:23 PM EST
Senate Armed Services Chairman John McCainJohn McCainGOP seeks to remove funding to design Gitmo alternative Big-name donors join Trump fundraising team Defense bill renews fight over military sexual assault MORE (R-Ariz.) says he is open to changing military pay and benefits for future servicemembers, a move fiercely opposed by military advocacy groups.
McCain told reporters that he "can probably support a number of changes that need to be made."
"In other words, anybody who has already joined the military is eligible for those pay and benefits, but as of a certain date, people joining may be subject to changes in those benefits," he said.
His remarks come just two weeks before a congressionally appointed commission is due to issue recommendations to lawmakers and the White House on reforming military compensation. The report is expected on Feb. 1.
The Defense budget, which is due at the same time, will not include those recommendations, but the White House is expected to review the report and issue its own opinion within 60 days.
Pentagon leaders and military advocacy groups are bracing for a fight.
Defense officials argue that pay and benefits are eating up too much of the defense budget, and their growth needs to be slowed.
But advocacy groups argue that personnel costs are just low-hanging fruit the Pentagon is reaching for, instead of taking more difficult steps to lower defense spending.
Congress has repeatedly rejected most of the Pentagon's proposals to slow the growth of pay and benefits, but last year, accepted some changes in the 2015 budget.
McCain, who will oversee Congress's 2016 Defense budget, said military healthcare costs are taking up 20 percent of the Pentagon's yearly spending.
"We know that it has to be reformed, everybody knows it has to be reformed," he said. "There's nobody I know that says you can continue as we've been going."