For Jimmy Carter, the great open-convention battle shaking the ranks of the increasingly nervous Democrats begins to look like an exercise in losing by winning.

The president has the delegates, his forces are tightly in control of the New York nominating convention 10 days away, and they have the almost-certain power to guarantee a first-ballot victory. They can do so by mustering the strength to adopt the binding rule governing the way delegates will vote.

Its language could not be clearer:

"All delegates to the national convention shall be bound to vote for the presidential candidate whom they were elected to support for at least the first convention ballot, unless released in writing by the presidential candidate. Delegates who seek to violate this rule may be replaced with an alternate of the same presidential preference by the presidential candidate or the candidate's authorized representative(s) at any time up to and including the presidential balloting at the national convention."

Since Carter won some 60 percent of the delegates in the long primary season, adoption of that one rule would put a seal on his renomination with the first convention roll call. Democrats have been taking only one ballot to nominate their presidential candidates over the last 28 years any how; this rule, new in political history, merely makes that behavior absolutely certain.

The trouble lies in the contentious, not to say panicky, atmosphere sweeping Democrats across the country. Carter desperately needs to emerge from the convention with the party as unified as possible behind him. Pressing the fight to adopt that rule, and thereby precluding the atmosphere of an "open" convention, virtually assures more bitterness and frustration among the already sorely divided Democrats.

That's why such strong supporters of the president as Connecticut's Gov. Ella Graso have come out in favor of opening the convention. They are not abandoning Carter nor rejecting the principles involved. It's victory in the fall they want. In this case compromise over a point of procedure seems preferable to standing firm and courting defeat by breeding new party antagonisms.

The dilemmas are exquisite and historic. They pit the politics of past precedent vs. the politics of reform, of conscience and free choice vs. control. The issue is emotional and deadly serious.

For Carter in particular, the situation involves the highest risk. If he instructs his delegates to defeat the binding rule, he hands Edward Kennedy and other opponents their only chance for success. In these volatile pre-convention days, with anti-Carter sentiment rising daily as each poll puts the president's ratings lower, as problems over his brother Billy's behavior continuing to increase, an open convention poses the possibility of a stampede against him.

But Carter quite possibly risks even more by not allowing fraction Democrats to vent their feelings and then rally behind their nominee -- still, by all odds, Jimmy Carter.

Behind this struggle lies a longer, but not less emotional one over whether a political party is controlled by bosses cutting deals in the back rooms or by people whose primary votes are honored at the nominating convention. In this battle, pro- and anti-Carter sides alike claim to be the forces of virtue.

The Democratic Party that assembles in New York is notably different in procedure and rule from the one that left the violence and anger of Chicago 12 years ago. That tumultuous convention, held in the wake of assassination, riots at home and war abroad, came close to destroying the party. Out of its bitterness came a reform movement that now reaches full bloom more than a decade later in New York.

A number of reform commissions in the intervening years have worked at eliminating the old brokered kind of convention. Gone is the so-called unit rule that permitted states to cast their votes in solid blocks no matter how divided the delegation. Now the primary votes of the spring result in proportional representation of delegates elected for their respective candidate choices in the convention summer.

Carter's political operatives argue that citizens who cast their ballots for a certain candidate in the primaries would be disenfranchised if the delegates chosen to express their preferences vote otherwise at the convention. And, they argue, the delegation selection rules adoption two years ago by the party have the same force as law.

They've gone one critical step beyond. They have sought to bind the delegates on the first ballot by calling on them to adopt the so-called "F.3.C." rule. Adoption would render the convention incapable of nominating anyone other than Carter. There is no precedent for such a rule, and none ever has ever been adopted before.

What strikes the greatest controversy today is the conflict between that proposed rule and the Democratic Party's charter and bylaws. The charter clearly expresses the principle that a delegate must be free to vote his conscience. Section 10 says:

"The Democratic Party shall not require a delegate to a Party convention or caucus to cast a vote contrary to his or her expressed preference."

Further, every Democratic convention has operated as the ultimate authority. No matter what rules have been proposed earlier, or have been operable during the primary period, the convention has the authority to change them -- and to take virtually any other action its delegates desire. Article One, Section One of the party's bylaws, for instance, lays out this principle:

"The National Convention is the highest authority of the Democratic Party, subject to the provisions of the Charter."

To the Kennedy people, the binding rule would render the convention impotent and relegate its delegates to the status of robots unable to change their minds even if they want to.

In the end, for all the history, theory and struggle for reform, the ultimate decision involves the hardest kind of practical politics. That choice is Carter's alone.

He can play it safe, ram home the adoption and gain renomination on the first ballot. But it's also possible that in so doing he would be winning the battle and losing the war.