IS IT POSSIBLE that the nation's political attention will be riveted on the Dakotas, North

and South, next year? It is. It's one of the charms of the American system of government that fierce contests in two states with less than 700,000 residents each could determine control of the U.S. Senate for two or four or even six years, and that those contests could turn, as races in such states have in the past, on the arcana of farm issues that are little known or incomprehensible to the citizens of most of the other 48 states.

But they're a matter of life and death, economically and politically, in the Dakotas; and all signs are that these two states and some of their neighbors of the Great Plains are in the midst of one of those farm revolts that sweep the American Midwest with almost as great a frequency, and impact, as the fall's tornadoes. North Dakota and South Dakota, as it happens, have the nation's largest concentration of farmers: one-fourth of their people still live on farms, and the entire economy of the state is responsive to the ups and downs of farm prices and profits. Farm issues, naturally, are the focus of politics there.

That's usually bad news for the party in power. Other states' economies depend on levels of wages, which wobble within relatively narrow limits; the farm states' economies rise and fall with farm profits and losses, which vary wildly. Naturally people want to use government to protect themselves against the ill effects of swings, such as current low prices and frequent foreclosures. So farmers, our largest class of entrepreneurs, inevitably generate a political demand for government assistance.

Farm-state Republicans as well as Democrats tend to respond favorably to those demands. Sen. Mark Andrews (R-N.D.) has denounced Reagan farm programs, and Sen. James Abdnor (R-S.D.) voted for the farm credit bill Mr. Reagan vetoed. Both senators are up for reelection next year, and both could face serious challenges. Each Dakota is represented by a single Democratic congressman- at-large, and both of these -- Rep. Thomas Daschle (D-S.D.), who sponsored the farm credit bill, and Rep. Byron Dorgan (D-N.D.), a critic of the big grain companies -- are considering running.

In other parts of the country, politicians don't discern a trend favoring either party, and a number of Democratic senators and potential challengers for Republican seats have surprised everyone by choosing not to run. But in the Farm Belt, and particularly in the Dakotas, there's a strong Democratic trend right now. It may not last past this season or past the rewriting of this year's farm bill; farm revolts have been known to vanish as suddenly as tornado clouds. But it's entirely possible that Sens. Andrews and Abdnor, assumed to be safe not long ago, may face serious challenges, and that on these races will hinge control of the Senate.