WASHINGTON — U.S. House and Senate conferees on the massive 2019 defense authorization bill met Wednesday to launch closed-door negotiations between the chambers’ competing drafts.

Lawmakers are expected to wrangle over troop levels, how many F-35s to buy, a ban on the Chinese telecom giant ZTE, House-backed cuts to certain Pentagon support agencies, Senate-backed changes to the Defense Department’s hierarchy and restrictions on F-35 sales to Turkey, among myriad other issues.

The Senate voted Tuesday to endorse instructions to conferees reaffirming support of NATO (ahead of U.S. President Donald Trump’s contentious summit with alliance leaders in Brussels this week) and to support Senate-backed expansion of the Committee on Foreign Investment in the United States (to give CFIUS more power to investigate and block foreign transactions).

At a news conference to kick off the talks, House Armed Services Committee Chairman Mac Thornberry, R-Texas, and Senate Armed Services Committee senior member Jim Inhofe, R-Okla., expressed confidence they would swiftly reach agreement on a conference report.

“I’ve felt for a long time there’s never been a three-hour meeting that couldn’t be done in an hour and a half,” Inhofe quipped.

Inhofe is standing in for SASC Chairman John McCain, R-Ariz., who has been battling brain cancer at home for months. Lawmakers said McCain is present in the bill’s spirit of service and its substance, but he would be missed at the talks.

“He is in constant contact with his staff with different ideas he has, and I’m sure he’ll be watching intently,” Inhofe said. “We’ll be — as we have for the last four months — be hearing from him vicariously through other people.”

The Senate bill is named for McCain, and the House delegation’s most likely concession to the Senate is to name the final bill for him, Thornberry said.

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“I never want to predict the outcome of conference provisions, but think it’s a pretty good bet the House will recede on the title of the bill so that it can be honored appropriately on behalf of Sen. McCain,” Thornberry said.

Both versions adhere to the significant defense spending boost set by the bipartisan two-year budget deal. Inhofe noted the bill would reflect Republicans’ defeat of Democrats’ insistence on parity for defense and nondefense spending.

“We have broken parity for the first time in eight years, and we’re going to take advantage of that,” Inhofe said.

The lawmakers are expected to reach a bipartisan agreement on a conference report for the 58th year in a row. The report would then need to be adopted by both chambers and signed by the president to become law.

HASC ranking member Adam Smith, D-Wash., said the bill is critical in orer to meet the needs of troops. He also lauded the bipartisan and orderly process through which it would become law.