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 Stanley KingOvernight Defense: Dems grill Trump Army, Air Force picks | House chair subpoenas Trump Afghanistan negotiator | Trump officials release military aid to Ukraine Democrats grill Army, Air Force nominees on military funding for border wall Bipartisan panel to issue recommendations for defending US against cyberattacks early next year 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 ReidBarr fails to persuade Cruz on expanded background checks Harry Reid warns Trump 'can be reelected' Homeland Security Republican accuses Navy of withholding UFO info 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 CruzState Department's top arms control official leaving Sanders NASA plan is definitely Earth first Trump judicial picks face rare GOP opposition MORE (Texas) and Rand PaulRandal (Rand) Howard PaulOn The Money: House votes to avert shutdown, fund government through November | Judge blocks California law requiring Trump tax returns | Senate panel approves three spending bills Paul objection snags confirmation of former McConnell staffer Defense bill talks set to start amid wall fight 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 GrahamSenate Judiciary Committee requests consultation with admin on refugee admissions Trump reignites court fight with Ninth Circuit pick Trump judicial picks face rare GOP opposition MORE (S.C.) and Marco RubioMarco Antonio RubioLiberal super PAC launches browser extension replacing 'Mitch McConnell' with 'Moscow Mitch' Trump faces difficult balancing act with reelection campaign Republicans wary of US action on Iran 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 KaineDemocrats hit Scalia over LGBTQ rights Missouri Republican wins annual craft brewing competition for lawmakers Sen. Kaine: No reason for US to 'engage in military action to protect Saudi oil' 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 McCainAmerica's newest comedy troupe: House GOP Michelle Malkin knocks Cokie Roberts shortly after her death: 'One of the first guilty culprits of fake news' Arizona Democratic Party will hold vote to censure Sinema 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 Energy: California, 23 other states sue Trump over vehicle emissions rule | Climate strike protests hit cities across globe | Interior watchdog expands scope of FOIA investigation | Dems accuse officials of burying climate reports Hillicon Valley: Lawmakers say Zuckerberg to 'cooperate' on antitrust probes | Dems see victory after McConnell backs election security funds | Twitter takes down fake pro-Saudi accounts Liberal super PAC launches browser extension replacing 'Mitch McConnell' with 'Moscow Mitch' 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 — Presented by Partnership for America's Health Care Future — Walmart to stop selling e-cigarettes | Senators press FDA to pull most e-cigarettes immediately | House panel tees up e-cig hearing for next week Hillicon Valley: Lawmakers say Zuckerberg to 'cooperate' on antitrust probes | Dems see victory after McConnell backs election security funds | Twitter takes down fake pro-Saudi accounts Bipartisan group of senators urges FDA to pull most e-cigarettes immediately 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.