Ideally, the presidential contenders vying in Puerto Rico -- where the Republican primary, the nation's first, will be held on Sunday and the Democratic primary on March 16 -- would be probing the question of whether the commonwealth may soon apply for statehood. But it's working out poorly, and that's too bad, for the issue is a potential time bomb of the 1980s in foreign and domestic terms alike.

The Republican campaigners are pushing statehood, which is where the Republican primary votes on the island are thought to lie. But this has produced some weird distortions. Ronald Reagan (who dropped out of the primary) wrote in The Wall Street Journal this week that, if elected, he's "take the lead in persuading the people of Puerto Rico" to grasp statehood.

Wait a minute. Reagan didn't say that he's accept the Puerto Ricans' choice among the alternatives of statehood, independence or a revised commonwealth. That's the only position consistent with true self-determination; the Democratic candidates have formally embraced it. He said he's lead Puerto Ricans toward his preferred outcome. That's the formula for tainting the very verdict he favors in both Puerto Rican and interntational eyes.

What is even more interesting is why he is promoting statehood: to set up a Puerto Rican model of free-enterprise development to compete with the Cuban model in peaceful competition throughout the Third World.

Our Sharks, their Jets: I find this an odd pitch to make to Puerto Ricans. For the legitimate, compelling and salable case for statehood is not that it would allow the mainland to draft Puerto Rico's 3.5 million citizens for special duty in the Cold War. It is that Puerto Ricans, if they chose it, would be claiming their full political rights as U.S. citizens.

There's something else. After he came out for statehood in his announcement of candidacy last November, Reagan says, "close friends" wondered why he would emphasize this "routine" issue while U.S. foreign policy was everywhere collapsing. Plainly, the Journal article meets his friends' anxieties: it transforms Puerto Rico into the sort of geopolitical issue that a conservative mainland constituency might understand.

Between the lines, I think, Reagan is communicating something troubling: that he and his friends are not all that enthusiastic about Puerto Rican statehood. I say this not merely because he dodges the question of political rights but because he holds out the chimera of an economic miracle. Moveover, there has been a subtle shift in his criterion for statehood: "a great majority of Puerto Ricans -- not just a simple majority -- [must] feel the pull of statehood with passion." Such a great and passionate majority is simply not in the cards.

I do not mean to single out Reagan. Carter's operatives in Puerto Rico have their own record of manipulation. Currently, some of them are talking self-determination out of one side of their mouth, sstatehood out of the other. sThey are even suggesting that Republican primary voters exploit a peculiarty of the local electoral law to vote a second time, this time for Carter, in the Democratic primary.

The main objection remains that the campaign is not producing much straight talk about statehood either in the island or on the mainland. In Puerto Rico the impression is being conveyed that Congress will readily grant any statehood petition the islanders present. In the United States the public is not being prepared to deal with the vexing questions a petition would pose.

Puerto Rico, which the United States acquired by its way with Spain at the turn of the century, is an American territory peopled by American citizens whose rights (and duties) are inferior to those of other citizens. that argues for honoring the islanders' choice of status, statehood included.

But Puerto Rico is relatively poor and undeveloped, a welfare drain, heavily non-white, Spanish-speaking, with a sense of separate peoplehood and a strain of political violence, perhaps basically Democratic, eager to claim two seats in the Senate and seven in the House. It take majorities in both houses to accept a new state, and these factors would surely slow many legislators down.

Would Congress finally put principle and moral obligation and a sense of a shared future first? Can its misgivings be discussed in a civil tone? Can the close and not always sympathetic attention foreigners will pay be kept from roiling our debate? Suppose Congress said no? These must be central elements in the statehood debate that we have scarcely begun.