The Senate passed a mammoth $750 billion defense bill Thursday, though it still needs to resolve a fight over Iran.

Senators voted 86-8 on the National Defense Authorization Act (NDAA), which authorizes spending and provides broad policy outlines for the Pentagon.

The bill provides $750 billion in total spending, including a base budget of $642.5 billion for the Pentagon and $23.3 billion for the Department of Energy’s national security programs.

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It also gives $75.9 billion for the overseas contingency operations fund, an account that does not fall under budget cap restrictions.

Republicans touted the mammoth bill as the most significant defense policy bill that Congress will pass this year. The NDAA has been signed into law for nearly 60 consecutive years, making it a lightning rod for a wide array of related and unrelated measures.

“It would be difficult to overstate the importance of this legislation to the ongoing missions of our nation's men and women in uniform. The NDAA is simultaneously a target to guide the modernization of our all-volunteer force, a supply line to restore readiness and keep U.S. personnel equipped with the most cutting-edge lethal capabilities, a promise of critical support services to military families and a declaration to both our allies and adversaries of America’s strategic resolve,” Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellTrump 'no longer angry' at Romney because of Supreme Court stance On The Money: Anxious Democrats push for vote on COVID-19 aid | Pelosi, Mnuchin ready to restart talks | Weekly jobless claims increase | Senate treads close to shutdown deadline The Hill's Campaign Report: Trump faces backlash after not committing to peaceful transition of power MORE (R-Ky.) said from the Senate floor.

In a boost to the administration, the Senate bill includes the administration’s request for $3.6 billion to “back fill” money the White House diverted from the military construction account as part of his national emergency declaration to build part of the U.S.-Mexico border wall. However, it does not include the administration’s request for an additional $3.6 billion in wall funding.

The bill garnered hundreds of amendments, with 93 wrapped into a manager's package that cleared without a formal Senate floor vote.

But, similar to previous years, votes on the heap of potential amendments quickly hit a roadblock over a fight about which proposals would be allowed to get a vote. Senate Armed Services Committee Chairman James Inhofe James (Jim) Mountain InhofeChamber of Commerce endorses McSally for reelection Overnight Defense: Top admiral says 'no condition' where US should conduct nuclear test 'at this time' | Intelligence chief says Congress will get some in-person election security briefings Top admiral: 'No condition' where US should conduct nuclear test 'at this time' MORE (R-Okla.) has blamed Sen. Rand Paul Randal (Rand) Howard PaulThe Hill's Morning Report - Sponsored by Facebook - Trump previews SCOTUS nominee as 'totally brilliant' Rand Paul says he can't judge 'guilt or innocence' in Breonna Taylor case Overnight Health Care: Health officials tell public to trust in science | Despair at CDC under Trump influence | A new vaccine phase 3 trial starts MORE (R-Ky.) for the roadblock, though Paul has argued that he can’t block the bill but wants an open amendment process.

"I do believe that we should demand that there's an open debate with amendments,” Paul told reporters late last week.

He's filed six amendments to the NDAA, including one repealing the 2001 war authorization and forcing President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE to withdraw U.S. troops from Afghanistan within a year and a second prohibiting indefinite detention. The two amendments have proved controversial in previous years.

In an unusual procedural move, the Senate is going to vote on an amendment to the defense bill on Friday morning, after they’ve already passed the NDAA.

The amendment from Democratic Sens. Tim Kaine Timothy (Tim) Michael KaineHillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Democrats call for declassifying election threats after briefing by Trump officials Buttigieg stands in as Pence for Harris's debate practice MORE (Va.) and Tom Udall Thomas (Tom) Stewart UdallLWCF modernization: Restoring the promise OVERNIGHT ENERGY: House Democrats tee up vote on climate-focused energy bill next week | EPA reappoints controversial leader to air quality advisory committee | Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' Senate Democrats demand White House fire controversial head of public lands agency MORE (N.M.) would block Trump from using funding to carry out military action against Iran unless he has congressional approval. Senators say if the amendment passes it will be added to the bill retroactively.

The Iran vote comes amid growing tensions between the United States and Tehran, and after Democrats threatened to block the defense bill until they were able to get a vote on the proposal.

McConnell initially indicated he would not wait until after Democratic senators running for president were able to return to Washington to hold a vote. But he announced from the Senate floor that the chamber would vote on the amendment Friday and hold the vote open until everyone was able to return.

Republicans are confident that they’ll be able to defeat the Iran measure because it will require 60 votes. With most Democrat expected to support the amendment, they would still need 13 GOP senators to attach the amendment to the defense bill.

“I don’t think it will get 60 votes,” Inhofe told The Hill. “I think it will have all of the Democrats. Democrats are disciplined, Republicans aren’t, we know that. And we know also that there are going to be a few Republicans that will join.”

The Senate bill still needs to be reconciled with the House, which plans to take up its version of the NDAA in July.

The two bills have considerable differences, including the dollar figure. The House bill would authorize $733 billion for defense compared with the Senate’s $750 billion.

There are also several provisions in the House version deeply opposed by Republicans, including prohibitions on the deployment of submarine-launched low-yield nuclear warheads and the use of Pentagon funding for a border wall.

House Democrats are also expected to pass amendments on the floor that would protect transgender military service members and block funding for military action against Iran, two more hot-button issues likely to gum up conference negotiations.

Both versions, meanwhile, would create a space military branch in line with Trump’s desire for a Space Force. But the two versions have differences in the name and structure of the new service that will have to be ironed out.