In 2008, the Democratic-controlled Senate passed a continuing resolution requiring lawmakers introducing new legislation to include a way to pay for any new spending they propose. “It shall not be in order in the Senate to consider any direct spending or revenue legislation that would increase the on-budget deficit or cause an on-budget deficit” for either a five-year or a ten-year period, said Senate Continuing Resolution 21.

Some observers might scoff — if that resolution is so important, how come we’ve had such huge deficits for so many years? But the resolution has been used a number of times to stop legislation that would have increased the deficit without providing a means of paying for itself. Sometimes that meant the bill was sent back to committee for amending, and sometimes that meant it was killed. But the resolution actually stood for something.

Not in the case of comprehensive immigration reform. The Congressional Budget Office found that the Gang of Eight reform bill would increase the on-budget deficit by about $14 billion in the coming decade. Any deficit reduction that would come from the bill would be the result of mostly-young, newly-legalized immigrants paying Social Security taxes but not collecting benefits until much later than the period examined by the CBO. (Most of what we consider government spending is known as on-budget spending; Social Security, which lawmakers like to think of as a special, dedicated fund, is considered off-budget, so for the purposes of the continuing resolution those tax revenues don’t count against the Gang of Eight deficit.)

So on Wednesday Republican Sen. David Vitter, a critic of the reform bill, raised a point of order objection against going forward with the Gang of Eight bill. It would increase the on-budget deficit, Vitter argued, violating Continuing Resolution 21.

What to do? The CBO report said in black-and-white that the bill will increase the on-budget deficit. And at the very least, raising the point of order was a way of highlighting the fact that any deficit reduction from the bill in the coming decade will come from those Social Security taxes from new taxpayers who will only later collect benefits. It didn’t look good. So what should the Senate do?

The bill’s supporters responded quickly, proposing a “Motion to Waive All Applicable Budgetary Discipline” that would allow the Senate to ignore its own continuing resolution. The motion required a supermajority to pass, and it easily got it, passing on a vote of 68 to 30.  (Two senators, Republicans Roy Blunt and Mike Lee, didn’t vote, although they would likely have been against it.)

Perhaps more than any test vote, the budget vote is probably a good predictor of the final vote on the Gang of Eight bill. The 68 “yes” votes included all 54 Democratic senators, and it seems likely they’ll all vote for final passage. As for Republicans, the people who voted to sustain the point of order are pretty much the core opposition to the bill: a maximum of 32 votes, if one includes Blunt and Lee. When final passage of the Gang of Eight bill comes, it will probably look like this vote.