ONE OF THE anomalies of the presidential selection process is that territories that are not eligible to vote in the general election nonetheless choose delegates to the national conventions. The largest of these is Puerto Rico, whose 3 million U.S. citizens will be represented by 56 Democratic and 14 Republican delegates in 1988. Unfortunately, in the fierce battle for these delegates, candidates often do damage not to their cause, but to the public life of Puerto Rico.

The most recent example comes in this year's Republican contest. George Bush, who won Puerto Rico's delegates in 1980 with the slogan "Statehood Now," met with a group of Puerto Rican leaders in Washington in April and left them believing he would push for legislation to admit Puerto Rico as a state; he then "clarified" this by saying he'd push for statehood if the people of Puerto Rico want it. This seemed insufficiently pro-statehood to some members of Puerto Rico's New Progressive Party, most of whom support Republicans in mainland politics, and in May Sen. Bob Dole flew twice to San Juan and said he'd introduce a bill to pay for a referendum on statehood between 1989 and 1994, and a pro-statehood group of mayors voted 11 to 0, with one abstention, to support his candidacy. In June, Mr. Bush flew to San Juan and one-upped that by supporting a bill that would require Puerto Rico to hold a referendum on its status.

All of this may sound like a petty bidding war. Holding out the promise of statehood has been a Republican tradition at least since President Ford did so in 1976. But the issue of status -- whether Puerto Rico should seek statehood, should retain the commonwealth status that leaves it a self-governing island under the American flag, or should become an independent nation -- is the central focus of Puerto Rico's politics and public life. It inspires such interest that turnout in Puerto Rican elections is higher than anywhere in the 50 states.

Mainland politicians should be careful not to tilt the balance by trumpeting promises of immediate statehood -- promises that Mr. Bush or Mr. Dole, in the high offices they now hold or the higher one they seek, would be hard put to deliver on. Mr. Dole wisely cautions that a "clear majority of Puerto Ricans must speak, must desire statehood" before Congress will grant it, and Mr. Bush says he'll push for statehood "only if the people of Puerto Rico want it." But these caveats are fine print next to the statehood headlines. Mr. Bush and Mr. Dole should be more careful of interfering in the sensitive internal politics of Puerto Rico.