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 KingHillicon Valley: Washington preps for Mueller report | Barr to hold Thursday presser | Lawmakers dive into AI ethics | FCC chair moves to block China Mobile | Dem bill targets 'digital divide' | Microsoft denies request for facial recognition tech Dems introduce bill to tackle 'digital divide' Collins receives more donations from Texas fossil fuel industry than from Maine residents 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 ReidSanders courts GOP voters with 'Medicare for All' plan Glamorization of the filibuster must end Schumer won't rule out killing filibuster 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 CruzO'Rourke sweeps through Virginia looking to energize campaign Disney to donate million to rebuild Notre Dame Celebs start opening their wallets for 2020 Dems MORE (Texas) and Rand PaulRandal (Rand) Howard PaulTrump vetoes measure ending US support for Saudi-led war in Yemen Bottom line Trump: I have not read Mueller report, 'though I have every right to do so' 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 GrahamWhy Ken Cuccinelli should be Trump's choice for DHS Ten post-Mueller questions that could turn the tables on Russia collusion investigators GOP senators double down on demand for Clinton email probe documents MORE (S.C.) and Marco RubioMarco Antonio RubioDems say attorney general undermined credibility with Trump talking point Pollster says there is no downside to Dems jumping into 2020 primary Senate confirms Trump's pick for ambassador to Saudi Arabia 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 KaineOnly four Dem senators have endorsed 2020 candidates Democratic proposals to overhaul health care: A 2020 primer Dems ask Justice Dept to release findings of Acosta-Epstein investigation 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 McCainTrump gives nod to vulnerable GOP Sen. McSally with bill signing Democrats need a 'celebrity' candidate — and it's not Biden or Sanders Juan Williams: The high price of working for Trump 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 McConnellThe Hill's 12:30 Report: Trump, Dems prep for Mueller report's release McConnell touts Trump support, Supreme Court fights in reelection video Why Ken Cuccinelli should be Trump's choice for DHS 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 DurbinCongress opens door to fraught immigration talks McConnell: 'Past time' for immigration-border security deal Overnight Defense: Transgender troops rally as ban nears | Trump may call more troops to border | National Guard expects 3M training shortfall from border deployment | Pentagon to find housing for 5,000 migrant children 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.