WASHINGTON  On the agenda is the revamping of the American health care system, possibly the most complex legislation in modern history. But on the table, in a conference room where the bill is being hashed out by six senators, the snacks are anything but healthy.

Last week, there were chippers  chocolate-covered potato chips  described on a sign as “North Dakota Diet Food.” More often, there are Doritos, pretzels, Oreo cookies and beef jerky: fuel to get through hours of talks on topics like the actuarial values of private insurance plans or the cost-sharing provisions of Medicare.

The fate of the health care overhaul largely rests on the shoulders of six senators who since June 17 have gathered  often twice a day, and for many hours at a stretch  in a conference room with burnt sienna walls, in the office of the Senate Finance Committee chairman, Max Baucus, Democrat of Montana.

President Obama and Congressional leaders agree that if a bipartisan deal can be forged on health care, it will emerge from this conference room, with a huge map of Montana on one wall and photos of Mike Mansfield, the Montanan who was the longest-serving Senate majority leader, on the other.