This post was updated at 10:30 a.m. ET
Congress votes on President Obama's nuclear deal with Iran this month. Most lawmakers have said they oppose the deal, yet he has a good chance of winning.
That is because the deal will be considered under rules that favor him, even if only a minority supports him in Congress.
That's the backdrop that led to a question I posed to the president in a recent interview: "Are you entirely comfortable going forward with a historic deal knowing that most of the people's representatives are against it?"
"Well, what I know is, is that unfortunately, a large portion of the Republican Party, if not a near unanimous portion of Republican representatives, are going to be opposed to anything that I do," Obama said.
So the White House and Congress are working around their mutual opposition. What follows is the story of how they do that on multiple issues.
The Iran deal is one example. The White House contends Congress has no business in that deal. It's an executive agreement, not a treaty. Lawmakers in both parties demanded a voice. Many dislike the deal — a lot.
When Secretary of State John Kerry appeared before Congress, Sen. Bob Corker described the agreement this way:
"From my perspective, Mr. Secretary, I'm sorry. Not unlike a hotel guest that leaves only with a hotel bathrobe on his back, I believe you've been fleeced."
So he said — yet Corker was among the architects of rules that make it hard to stop the deal.
Lawmakers sometimes set up votes to oppose important measures that they know will likely take effect anyway.
"Creative means, or desperate means, however it may be, are the order of the day," said Norm Ornstein of the American Enterprise Institute.
He's watching Corker, who's chairman of the Senate Foreign Relations Committee and "a very strong, legislative-minded, policy-minded guy," according to Ornstein. He's also a guy in a tough spot.
Corker has known for some time that the president and the United Nations were on their way to approving the Iran agreement. "Once the president has made a deal with all these other nations, endorsed by the U.N. Security Council," said Ornstein, "if Congress votes to block it, it's not going to look good for anybody — the country or them. So, you find a way to make it work."
They found a way within the arcane rules of congressional voting — borrowing an old mechanism used in civilian nuclear agreements.
Here's how it works. Instead of voting on whether to approve the Iran deal, Congress votes on whether to disapprove.
If they disapprove, the president can veto their disapproval. And under the normal rules, it would take two-thirds of the House and the Senate to override the veto. That makes all the difference.
We asked NPR editor Ron Elving how this changes the number of votes the president's side needs.
"If it were normal legislation and not a treaty, you would need 60 to shut off debate and then 51 to prevail," he said. For a treaty, 67 votes would be needed.
So how many does the president need for this deal? Thirty-four, said Elving. "That's the essence of what we're talking about here. If the Senate gives the president 34 votes to sustain his veto, he has won and it's over."
The president can also win without a veto, if a minority of 41 senators sustains a filibuster. All the checks and balances that make congressional action difficult work in the president's favor because his opponents, not Obama, are the ones who need Congress to pass something.
As of Wednesday, 34 Democrats had already voiced their support for the deal, with a number of others undeclared.
That means even if Republicans all vote no — and even if Democratic skeptics like Sen. Charles Schumer of New York also vote no — it looks like the president will have enough votes to prevail.
"It is a mechanism by which lawmakers can deal with the contradictions that reality presents them. You can call it cynical, you can call it pragmatic, but it gets the job done," Elving said, "both in the sense of keeping the government going forward and in the sense of solving the political problem of the individual lawmaker."
This happens more often than you might think. Consider a story we heard recently from Republican Sen. Ted Cruz of Texas, a Tea Party favorite and presidential candidate.
He told us about a Senate Republican lunch in 2014 where party leaders planned to change the voting rules for an increase in the federal debt ceiling.
"That Tuesday lunch began with our leadership saying, 'We're asking every Republican senator here to affirmatively consent to lower the threshold to take up the debt ceiling, from 60 votes to 50 votes,' " he said.
The change meant no Republican would have to join the effort to pass the debt ceiling hike.
Here's how Cruz described the Republican thinking: "The Democrats will have the votes to do it on their own, which means all of us Republicans can vote no. And we can go home and tell our constituents we opposed the thing we just consented to allow happen."
Cruz accuses his party leaders of "mendacity" — he says they're misleading voters.
Elving said lawmakers were working around people like Cruz.
"And that is a Washington solution," he said. "Ted Cruz is not wrong about that."
Lawmakers have used variations on this solution over the years. A dramatic one came in the debt ceiling confrontation in 2011.
Congress approved a rule that let President Obama raise the debt ceiling, even as majorities in Congress voted their disapproval.
Ornstein views this philosophically. "What Republicans in Congress have tried to do, the leaders, who first and foremost are pragmatists — they've got to find ways to accommodate the rowdy radical wing of their party," he said, "and yet still keep disaster from befalling them by bringing the place to a halt or having them blamed for terrible things that happen."
For generations, Democrats and Republicans alike found ways to let individual lawmakers vote no if their votes weren't really needed.
"This is called passing the buck and pointing the finger. And it is a long tradition," Ornstein said.
Today's partisan atmosphere leads to more dramatic tactics.
Certain mechanisms let a whole party vote no without affecting the outcome.
"If you didn't come up with mechanisms, you could have not just a sort-of gridlock but a real gridlock, and it could lead to catastrophic results," said Ornstein.
Lawmakers will use such a mechanism for the Iran vote this month. Then, another confrontation looms — over the federal budget.
It's possible lawmakers could find agreement not on substance but on how they vote.
It's a representative democracy, where the majority rules. Except when the majority agrees in advance that they won't.