Senate Democrats on Wednesday joined with Republicans to approve an annual defense bill, defying a veto threat from President Obama.

The Senate voted 70-27 in favor of the $612 billion National Defense Authorization Act (NDAA), a wide-ranging measure that would set policy and spending priorities for the Pentagon. Twenty Democrats voted yes, as did Sen. Angus KingAngus KingOvernight Energy: EPA watchdog slams agency chief after deputy fails to cooperate in probe | Justices wrestle with reach of Clean Water Act | Bipartisan Senate climate caucus grows Bipartisan Senate climate caucus grows by six members Senators fear Syria damage 'irreversible' after Esper, Milley briefing MORE (Maine), an Independent who caucuses with Democrats.

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While the vote total would be enough for Republicans to override Obama’s promised veto, Democratic leaders insist that some of their members would vote differently if asked to override the president.

“The president is going to veto this. Everyone knows this,” Senate Minority Leader Harry ReidHarry Mason ReidHarry Reid: Early voting states Iowa, New Hampshire 'not representative of the country anymore' The Memo: Democrats confront prospect of long primary Bottom Line MORE (D-Nev.) said ahead of the vote. “The House, if they are called upon first to sustain the veto, they will do it. If we’re called up on first to sustain the veto, we will do it.”

Republican Sens. Ted CruzRafael (Ted) Edward CruzSenate approves stopgap bill to prevent shutdown DNC raises million in October in best monthly haul of the year Supreme Court weighs lawsuit pitting climate scientist against skeptics MORE (Texas) and Rand PaulRandal (Rand) Howard PaulTrump steps up GOP charm offensive as impeachment looms Trump lunches with two of his biggest Senate GOP critics Senate approves stopgap bill to prevent shutdown MORE (Ky.), who are both running for president, were the only Republicans to vote against the bill. Two other 2016 candidates, Sens. Lindsey GrahamLindsey Olin GrahamFBI official under investigation for allegedly altering document in Russia probe: report Trump steps up GOP charm offensive as impeachment looms Graham requests State Department documents on Bidens, Ukraine MORE (S.C.) and Marco RubioMarco Antonio RubioHouse Democrat asks USDA to halt payouts to Brazilian meatpacker under federal probe Supreme Court weighs lawsuit pitting climate scientist against skeptics Senate passes legislation supporting Hong Kong protesters MORE (Fla.), didn't vote.

The policy bill has been pulled into the larger battle over the GOP’s budget plan, which would appropriate $38 billion to the Pentagon through a war fund account.

Democrats and the White House say the war fund should not be used to skirt congressional budget caps and are demanding that Republicans negotiate a deal to raise spending across the federal government.

But Republicans, and even some Democrats, have questioned why Obama is poised to veto the NDAA, as the bill authorizes spending without actually appropriating the money.

"You know, I started to have conversation with the White House when we were taking this up in committee, telling them their veto threat was a mistake," said Sen. Tim KaineTimothy (Tim) Michael KaineOvernight Defense — Presented by Boeing — Deal on defense bill proves elusive | Hill, Holmes offer damaging testimony | Trump vows to block Navy from ousting officer from SEALs Pentagon No. 2 denies trying to block official's impeachment testimony Overnight Health Care: Trump officials making changes to drug pricing proposal | House panel advances flavored e-cig ban | Senators press FDA tobacco chief on vaping ban MORE (D-Va.), who voted in favor of the NDAA on Wednesday.

"To basically say you'll veto over the [war fund] issue, when we have language in the bill that basically says we should fix the budget caps, I said, 'I think you're drawing the line in the battle at the wrong place.' "

The policy bill has passed Congress for 53 consecutive years, and is typically considered one of the most important legislative tasks for Congress.

Sen. John McCainJohn Sidney McCainFormer McCain adviser warns Democrats of going left: A 'sociopath' will always 'beat a socialist' Budowsky: Trump destroying GOP in 2018, '19, '20 Conservative group cuts ties with Michelle Malkin MORE (R-Ariz.), the chairman of the Senate Armed Services Committee, said an Obama veto of the defense bill would be “shameful.”

“If the president vetoes the NDAA, at this time of mounting global threats, he will be prioritizing politics and process over the security of our nation and the well-being of our armed forces.”

Majority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellOvernight Defense — Presented by Boeing — Deal on defense bill proves elusive | Hill, Holmes offer damaging testimony | Trump vows to block Navy from ousting officer from SEALs Trump steps up GOP charm offensive as impeachment looms Congressional authority in a time of Trump executive overreach MORE (R-Ky.) echoed that criticism Wednesday.

“If he does [veto the bill], it will be the latest sorry chapter in a failed foreign policy based on campaign promises rather than policies to realistically meet the threats before us,” he said.

Obama has threatened to veto the policy bill six times before, primarily due to objections on the transfer of prisoners from the Guantánamo Bay prison facility, but never followed through.

But this year will be different, the administration says, due to the president's strong objections to the use of the war fund.

Press secretary Josh Earnest this week called the GOP plan an “irresponsible way to fund our national defense priorities” and reiterated that Obama would reject it.

Rep. Mac Thornberry (R-Texas), the chairman of the House Armed Services Committee, suggested that if Obama vetoes the bill, it would be different from the four times the NDAA has been vetoed in the past 53 years.

"Every one of them were because of something that was in the bill, not because of something that was outside bill, which is thing the president is complaining about today," he said.

If and when Obama’s veto comes, Republicans are likely to try for an override, though success appears unlikely. The House fell short of the two-thirds majority needed to override a veto when it voted on the NDAA last week. And Sen. Dick DurbinRichard (Dick) Joseph DurbinOvernight Health Care: Crunch time for Congress on surprise medical bills | CDC confirms 47 vaping-related deaths | Massachusetts passes flavored tobacco, vaping products ban Trump, senators push for drug price disclosures despite setbacks Tensions rise in Senate's legislative 'graveyard' MORE (D-Ill.) warned on Tuesday that Republicans should not assume that Senate Democrats voting for the NDAA would also vote to overturn Obama’s veto.

"If we can't override [a veto] ... outside events will dictate the future and the fate of the legislation," McCain said. "We need 67 in the Senate. It will be very interesting to see how many we hold."

Some military groups have warned Obama against holding the policy bill hostage to the larger funding fight. 

The Military Officers Association of America (MOAA) and the Reserve Officers Association have both sent letters to the president urging him to support the NDAA.

MOAA President Norbert Ryan Jr. said while the concerns about the extra war funding are “legitimate,” the policy legislation “is vital to fulfilling wartime requirements.”

— This story was updated at 5:19 p.m.