IT MAY NOT win good ratings, but the longest television saga going may well be the coming of cable to the District of Columbia. Like the soaps, this story is loaded with false endings and intricate maneuvers, each destined to keep everyone hanging. In the last installment, the local government chose between three suitors, deciding for legitimate reasons to link up with District Cablevision Inc., a company with strong local ties and a sound contractual connection with the local telephone company to wire up the city. Negotiations are under way now, and after a rough opening round in which both city and cable firm put forth proposals they knew would have to be modified, there is said to be progress. Enter the two loser- suitors, with attempts to block the marriage by going to higher authorities -- in the federal government.

One run to the federal government is by Capital City Cable, which is seeking intervention by the Justice Department. An attorney for Capital City claims that the Chesapeake & Potomac Telephone Company's involvement (even though it is only to do the wiring job) raises questions about whether the cable system would be able to compete with the telephone company in other ways. Both C&P and District Cablevision say that competition could -- and likely will -- occur; besides, it can be stipulated formally, in any agreement.

But the challenging losers also are seeking to pull the issue into court, by claiming that C&P should be required to seek a waiver from the decision under which AT&T was broken up. The second losing bidder, District Telecommunicatins Development Corp., apparently has still other plans. One investor in this firm called the attempt to get the Justice Department involved "just the first cannon fire."

So look for lots of other action, probably including attempts to get still other action in the Federal Communications Commission. Meanwhile, the city cable negotiating team has a six-month period in which to reach a contract agreement with District Cablevision. It is here -- on the local level -- that a sound agreement can and should be reached, one that will hold up under federal and local law, without need for a string of appeals to federal authorities that could delay cable even more than the process has already.