Lawmakers said yesterday they were close to crafting a compromise Pentagon policy bill, following multiple meetings of the four key House and Senate negotiators, though some key matters remained unresolved.

The official House-Senate conference committee that will approve a final fiscal year 2013 defense authorization bill had not met as of last night. Yet the chairmen and ranking members of the House and Senate armed services committees have met informally more than once.

“We’re making good progress,” Senate Armed Services Committee (SASC) Chairman Carl Levin (D-Mich.) said yesterday afternoon, before one of those gatherings of the “big four” lawmakers.

“I don’t see any real sticking points,” SASC Ranking Member John McCain (R-Ariz.) said around the same time.

McCain gave one of the most optimistic predictions of when the conference committee could agree on a final bill, predicting last night or today. Other lawmakers including Levin surmised a compromise bill could be ready by early next week. Yet plans for an official House and Senate conference committee meeting to be held today were uncertainlate yesterday, when the House delayed a vote to officially name its conferees last night. The Senate named the entire SASC to the conference committee last week.

As of yesterday afternoon HASC and SASC leaders hadn’t yet resolved some differences between the versions of the authorization legislation, which passed the House in May and the Senate last week.

Those include a provision in the Senate bill requiring defense contractors with classified information to alert the government when their computer systems are hacked, McCain said. The House and Senate negotiators also had not yet decided as of yesterday afternoon whether to keep House language forbidding the Pentagon from killing the Global Hawk Block 30 unmanned aircraft program, a source said.

The House-and-Senate-passed bills clash on several high-profile proposals, including whether to keep House language restricting the Pentagon’s alternative-energy work and directing it to plan for an East Coast missile-defense site.

In addition to the recent informal meetings of the “big four,” HASC and SASC staff have been meeting since the pre-election congressional recess to hash out sundry differences between their two bills. Yet staff saved some controversial matters to be decided by the four committee leaders.

Lawmakers and aides predicted the House and Senate will have a final conference committee-approved defense bill by early next week, so each chamber can cast final votes to approve it next week.

The White House, though, has issued presidential veto threats for both the House and Senate bills, citing qualms with matters ranging from military detainees to prohibitions on retiring aircraft.