The United States, Russia, China, France, Britain and Germany want to ensure that Iran's nuclear program doesn't let it produce nuclear weapons. But doubts about a deal to curb the program are growing as the deadline nears.
Iran wants an easing of economic sanctions and latitude on the program; the so-called P5+1 group on the other side of the table wants assurances that Iran's nuclear advances have no possible military use. Three scenarios exist: a deal, no deal or an extension.
If there's a deal
For oil traders, a deal means the possibility of more Iranian crude coming to the market, meaning more supply of a commodity that's already trading at $79 a barrel, down 23 percent in the last three months. Naturally, the markets will anticipate prices declining further.
If there's no deal
If there's no deal, that would likely trigger additional sanctions from Congress. Last year, Sens. Mark Kirk, R-Ill., and Robert Menendez, D-N.J., co-authored a sanctions bill that has been held up by Senate Majority Leader Harry Reid, D-Nev., under pressure from the White House.
In January, however, when the 114th Congress is sworn in, Reid will be replaced by Sen. Mitch McConnell, R-Ky. A Republican staffer said Wednesday of the proposed sanctions, "that bill will definitely be on the agenda."
The Kirk-Menendez bill has 60 co-sponsors, and because of the makeup of the incoming Senate and the fact that preventing Iran from having nuclear capabilities is a popular bipartisan issue, those 60 are likely to grow to a veto-proof 67 quickly.
That could mean a sharp increase in the price of oil.
"If there is no deal, prices will rebound not only because of expectations of lost Iranian output but also because tensions will rise between Iran and Western countries," said energy trader John Kilduff, founding partner of Again Capital.
Oppenheimer's Fadel Gheit agreed, telling CNBC that global tension feeds supply concerns and boosts oil prices. But the arithmetic may not be so simple in the longer term.
"Higher oil prices would dampen growth and increase supply, setting the stage for another drop," Gheit said.
If there's an extension
If Iran and the P5+1 believe they're close to a deal but can't quite get there by Nov. 24, both sides could agree to a second extension of the deadline. But this time Republicans in the House and Senate are unlikely to allow it to be consequence-free, meaning they'll roll back allowances given to Iran a year ago.
Even if there is a deal and Congress doesn't think it's tough enough, the legislative body is likely to make it difficult for President Barack Obama to move forward. Congress could try to close loopholes on existing sanctions or cut off access to overseas escrow accounts Iran uses in order to do business and access cash abroad.
It's also still unclear whether supreme leader Ayatollah Ali Khamenei would allow President Hassan Rouhani to make a deal anyway.
A senior senate staffer familiar with the drafting of Iran sanctions summed up the drama this way: "We're at the point where the ayatollah will have to make his call."