WASHINGTON — The U.S. House and Senate conferees on a massive 2018 defense authorization bill met Wednesday to launch negotiations between the chambers’ competing bills.

Lawmakers are expected to wrestle over a House proposal to create a new Space Corps as well as the size of the Army and the total number of F-35 fighter jets — among myriad other provisions. Staffers have been working for weeks, and this pass-the-gavel meeting was the first formal sit-down.

At a news conference to kick off the talks, Senate Armed Services Committee Chairman John McCain, R-Ariz., and House Armed Services Committee Chairman Mac Thornberry, R-Texas, told reporters they expect to find agreement on a conference report quickly.

“There is a widespread consensus that we need to do better for our military,” Thornberry said. “Just like Sen. McCain said, I am optimistic that we can deliver better in a pretty short amount of time given the similarities between the House and Senate bills.”

Both versions propose increases well above the president’s defense budget request. The Senate bill calls for $640 billion in Pentagon and other national security spending, blowing past the $549 billion limit set by statutory budget caps. The House bill calls for $621 billion in national security spending.

Complicating matters, there’s no consensus on lifting budget caps or a broader budget deal for fiscal 2018, and the federal government has been operating on a stopgap spending measure, called a continuing resolution, since last month.

The HASC’s top Democrat, Rep. Adam Smith, of Washington, used the news conference to lament the use of continuing resolutions and urge the passage of appropriations and defense policy bills.

“Month to month, week to week is no way to go,” Smith said. “We have to get an authorizing bill passed and an appropriations bill passed. If the money is there, the men and women serving in uniform at least know what is being asked of them.”

For his part, McCain continued to link defense budget caps to recent mishaps in which dozens of troops were hurt or killed, describing it as a “critical situation.”

“This legislation cures some of those problems but they’ve been building up for a long time,” McCain said. “The responsibility to a large degree lies with the Congress of the United States for not providing sufficient funds for them. We hope to turn it around this time.”

The House named 46 Republicans and 27 Democrats as conferees, while the Senate sent every member of the SASC, 14 Republicans and 13 Democrats.

The lawmakers are expected to reach a bipartisan agreement on a conference report for the 56th year in a row. Thornberry noted the House passed its bill with 79 percent of the vote and the Senate passed its bill with 89 percent.

The conference report would then need to be adopted by both chambers and signed by President Donald Trump to become law.