CAPITOL HILL: Chairmen of the House and Senate Armed Services committees take pride in the fact their panels have gotten 53 annual defense bills in a row through the often tortuous negotiations required to clear Congress.

And Sen. John McCain, chairman of the Senate Armed Services Committee, has often made known his view that the National Defense Authorization Act (NDAA) really matters and must be passed before the money men — the appropriators — pass their bills.

President Obama’s administration has threatened to veto the bill, but they’ve done it at the level of we-really-don’t-like-this-bill-but-we’re-not-willing-to-say-the-president-WILL-veto-it. Instead, the administration used the same threat it has used for at least the last five years: senior officials would recommend the president veto the bill.

McCain, speaking at the Heritage Foundation today, said he’d spoken this morning with Defense Secretary Ash Carter, who told the senator that he would recommend the president veto the bill.

“I’m very much afraid he will,” McCain told the audience. The chairman said he thought it would be a mistake since this is a policy bill — not a money bill — and the Democrats have made clear they believe the bill’s flaws reside principally with the fact that Republicans added $38 billion to the Overseas Contingency Operations (OCO) account as a way to bypass the Budget Control Act caps and ensure the Pentagon got all the money it requested.

Sen. Jack Reed and Rep. Adam Smith, the ranking members of the SASC and HASC, urged their Democratic colleagues to oppose the 2016 NDAA. Both chambers passed their respective versions of this year’s bill despite that. The conference committee and professional staff are now hammering out the final bill, which is expected sometime later this week or next.

So let’s take a quick look at just what some folks who’ve actually helped build the NDAA say about Obama’s veto threat, whether he’ll carry it out and what it would it mean if he does.

After McCain spoke, Heritage put on a panel comprised of Todd Harrison, the go-to defense budget expert at the Center for Strategic and Budgetary Assessments; Roger Zakheim, former HASC deputy staff director and now at the American Enterprise Institute; and John Bonsell, former SASC minority staff director and now VP for government affairs at SAIC.

Harrison and Bonsell said they didn’t think President Obama would veto the bill, partly because it’s not the money bill and partly because he hasn’t done so in the past. And, Bonsell noted, troops won’t get paid if the NDAA isn’t law by the end of September.

Zakheim was not as “sanguine.” He noted the president is “highly motivated.” But he also pointed out that if Obama does veto the bill, then it won’t get fixed “until after the appropriations bill is done.” And that would be late in 2015 or early 2016, So the stakes are high.

Bonsell said the real worry facing everyone is the appropriations bill. Congress is not likely to pass the major spending bills until late in the year. “We are headed for a major crisis at the end of the year,” he said. We face another Continuing Resolution to get us through December. And everyone will have to decide if they are willing to live with the consequences of the Budget Control Act.

Bonsell argued Obama would be “wasting a veto now on the authorization bill. He’d just be wasting his influence.” And Obama’s influence will be greatest at the end of the year, when the crisis hits.

But I asked the panel if they thought vetoing the NDAA would set a political marker, one that might encourage Republicans to reconsider the costs of trying to dodge the pain of the Budget Control Act and give the military what the administration says it needs.

Bonsell and Harrison thought not. Zakheim, clearly the wisest of the three, said he thought it might help create the “manufactured criss” that Washington needs to fix a problem. “Maybe it accelerates the crisis a little,” he said.

In the meantime, the House and Senate conferees are hammering out a bill. One of the biggest areas of uncertainty has to be (so far no one is talking) how far Rep. Mac Thornberry, HASC chairman, is willing to go and accept the much more ambitious acquisition reforms contained in the Senate version of the bill.

McCain’s push to move more acquisition power to the four uniformed service chiefs has many acquisition experts worried that he’s undercutting the powers of the civilian undersecretary for acquisition, technology and logistics. Thornberry’s bill was much more modest in its reform proposals.