NEW YORK'S Republicans are showing themselves once again to be foes of genuine political competition, and George W. Bush, the likely beneficiary, is cheering them on. They have resolved to bar all but two candidates from their presidential primary. The state's Byzantine registration system, which can be mastered only with big bucks and big lawyers, already has excluded Gary Bauer, Orrin Hatch and Alan Keyes. Now New York's Republican bosses are preparing a lead coffin for John McCain's candidacy.

This stifling of electoral competition is only slightly more obnoxious than the reaction from the Republican front-runner, George W. Bush. Mr. Bush has the most to gain from New York's exclusion tactics, since only he and Steve Forbes are on the ballot, and since Mr. McCain is the closest thing he has to a threatening rival. Time and again, Mr. McCain has demanded that Mr. Bush instruct his New York supporters not to put up legal obstacles to his appearance on the ballot. But Mr. Bush has washed his hands of the issue. "It's a decision for the state party to make," a Bush spokeswoman says.

The truth is that the Republicans' choice of presidential candidate is not merely a local issue. New York is the nation's third-most populous state, and its primary is early enough to exert considerable influence over the outcome of both parties' primaries. If the Republican contest is rigged, that is a national scandal. It's sad that Mr. Bush, who is comfortably ahead of Mr. McCain in both money and national polls, cannot bring himself to say so.

This is the third issue that Mr. Bush has ducked by describing it as local. Last year he declined to condemn creationist teaching in Kansas; recently he has declined to criticize South Carolina's habit of flying the Confederate flag. As a state governor, Mr. Bush no doubt believes deeply in the principle of state autonomy.

But as a candidate for president, he should not withhold his opinion on matters such as the flag and ballot-fixing. Even if presidents lack the power to resolve all such issues, they are expected to use the bully pulpit to guide the country in dealing with them.

At this stage, Mr. Bush may be more interested in winning the presidency than in reflecting upon its functions. Yet that would be mistaken: If he develops a reputation for expediency now, he will be taken less seriously as a leader later. Mr. Bush need only look at Bill Clinton to see a man whose campaign style defined and circumscribed his presidency.