Sen. Jesse Helms announced last week that it was his "intention" to fulfill a campaign promise and remain on the Senate Agriculture Committee, where he now serves as chairman, a position that gives him maximum ability to protect the tobacco interests of North Carolina.

Friends of the Foreign Relations Committee might have initially breathed a sigh of relief that the senator would then have to forgo the chairmanship of that committee, but it may be too early to relax.

Consider the careful choice of the word "intend," a slippery term describing a present state of mind but offering no guarantee for the future. The president, we are assured, does not "intend" to raise our taxes. But few would be surprised if "conditions change" or "things do not work out as he had hoped," and sometime down the line he "is forced, reluctantly" to sign a revenue bill.

There is plenty of room for maneuver in Helms' situation, and there may be opportunities for him to respond to a change in circumstances by reconsidering his present intentions. Consider this scenario:

*Sen. Robert Dole of Kansas, now chairman of the Senate Finance Committee and one of the five men contending for the majority leadership post in an election to be held the week after Thanksgiving, has second thoughts about the race. Some conservatives who would ordinarily support him do not want the important Finance post to go to liberal Sen. Robert Packwood of Oregon, and may be reluctant to promote the Kansan out of that job. Knowing this, he counts his votes and decides he doesn't want to run the risk of a defeat that would tarnish his 1988 presidential hopes, and drops out of the race.

*Sen. James McClure of Idaho, a personally popular contender, finishes first in the initial round of voting, but does not have a majority. McClure is then perceived by Helms' partisans as a rival for leadership of the right, and in the second round of voting, a sufficient number are quietly persuaded by the North Carolina senator to switch their votes. Their choice, and a clear winner in this situation, is Sen. Richard Lugar of Indiana.

*Lugar becomes majority leader, which removes him from the line of succession on the Agriculture Committee, where he is right behind Helms. Next in line is Sen. Thad Cochran of Mississippi, a conservative with agricultural interests of his own to protect. He poses no threat to the tobacco farmers, as would Lugar, and it would be safe for Helms to leave the committee in his hands.

*At this point it would not only be acceptable for the North Carolina senator to move to the chairmanship of Foreign Relations, it would be demanded by the right, because Lugar, if he were elected majority leader, could not assume the chairmanship of Foreign Relations, as he is now slated to do. That would leave the committee in the hands of one of the few remaining old-line liberals in the Republican Party, Charles Mathias of Maryland.

The scenario works beautifully for Helms. Three important committee chairmanships are kept from the liberals, a decent, middle-of-the-road man is majority leader, and the senator from North Carolina retains his national prominence on the right and becomes the head of the Foreign Relations Committee. Tobacco subsidies are safe, and the Agriculture chairmanship has been abandoned only when his national constituency pleads with him to change his mind and move to a spot where he is critically needed to protect its interests. Don't be surprised if "unforeseen events" and "pressures from his friends" force the North Carolina senator to revise his plans and, coincidentally, put him right where he wants to be.