Washington -- Pat Buchanan is ''Irish confetti'' for George Bush.
Parts of Manhattan were paved with extremely hard Belgian stones (Romans used such stones on the Appian Way), which first served as ballast in lightly-loaded ships coming to America. Irish immigrants, including some as turbulent as their descendant Buchanan, expressed disagreements with cops by chucking Belgian stones at them. The cops called these bone-breaking showers, ''Irish confetti.''
Mr. Buchanan, the pugnacious political aide (to Presidents Nixon and Reagan) and commentator, is challenging Mr. Bush for the Republican nomination, beginning in New Hampshire, where a Boston Globe poll gives Mr. Bush an approval-disapproval rating of 42-47.
Republican discontent is finding many forms of expression. For example, Democratic candidate Bill Clinton received a respectful hearing last week from influential Republicans in Southern California's Orange County.
Mr. Buchanan may be particularly troubling to the president because he is two things Mr. Bush is not: articulate and ideological.
Consider Mr. Buchanan's budget-cutting strategy. It is to propose deep cuts and when Congress rejects them, to veto Congress' appropriations bills or continuing resolutions.
The result would be havoc, recrimination, polarization: President Buchanan in his element. Then the government shuts down. Bliss! Social Security recipients raise hell. President Buchanan tells Congress: I'll sign only what it takes to keep Social Security flowing.
Mr. Buchanan favors ''the politics of confrontation. Consensus, compromise haven't done it for 25 years. Why not try something new.'' Grab a stone.
The Buchanan style may appeal to working class and lower-middle class former Democrats who recently have voted Republican and now, polls show, are the most disaffected Americans. David Duke is after them, too.
Mr. Buchanan rightly insists that David Duke's use of such issues as welfare dependency and racial quotas does not make those issues off-limits for decent politicians. Hitler built autobahns; Eisenhower was not Hitlerean because he built the Interstate Highway System. Anti-Communism was right even though Joe McCarthy was an anti-Communist.
Furthermore, one function of insurgent candidacies, within and outside the two parties, from Robert La Follette, Eugene Debs and Norman Thomas through George Wallace and Eugene McCarthy, is to put topics on the table that more conventional politicians are too timid to touch.
One such topic today is immigration. It brings out Mr. Buchanan's strength -- his eagerness to talk about whatever is troubling people -- and his weakness: Do not expect from him nuances of thought or delicacy of expression.
He correctly warns that there can come a point when indiscriminate diversity in a population produces national incoherence by blurring identity and diluting community feelings. He is right that ''culture, language, background are not illegitimate criteria for us to discuss when we discuss legal immigration.''
But it won't do to say, as he does, that a million English immigrants would be easier for Virginia to assimilate than a million Zulus. The English are not knocking at the door. The real policy questions concern people of many other cultures.
''Who,'' he asks, ''speaks for the Euro-Americans who founded the U.S.A? . . . Is it not time to take America back?'' In what sense ''take back''? Back from whom?
''No one,'' he says, ''questions the right of the Arabs to have an Arab nation, of China to be a Chinese nation. . . . Must we absorb all the people of the world into our society, and submerge our historic character as a predominantly Caucasian Western society?'' Gracious. ''All the people of the world''? ''Submerge''? Such hyperventilating is not helpful.
Besides, Mr. Buchanan evidently does not understand what distinguishes American nationality and should rescue our nationalism from nativism. Ours is, as the first Republican president said, a nation dedicated to a proposition. Becoming an American is an act of political assent, not a matter of membership in any inherently privileged or especially appropriate group, Caucasian or otherwise. The ''Euro-Americans'' who founded this nation did not want anything like China or Arabia -- or any European nation, for that matter.
Mr. Buchanan formally launched his ''America First'' campaign two days after the Soviet Union formally expired. His most lurid liability is his wrong, sometimes mean and occasionally crackpot ideas regarding Israel, the Holocaust and the politics of American Jews.
These ideas will not matter immediately for three reasons: The Jewish vote is not crucial in Republican presidential primaries; no foreign policy questions will be central just now and Mr. Bush is semi-Buchananesque regarding Israel.
Mr. Bush has made the executive branch into a megaphone to turn American attitudes against Israel. Besides, voters will, at least initially, look at Mr. Buchanan not as a potential president but as a megaphone for hollering in Mr. Bush's ear.
Mr. Bush may come to envy New York's 19th century cops. They got the city to put asphalt over the Belgian stones. The president's solution to his ''Irish confetti'' problem may not be so simple.
George F. Will is a syndicated columnist.