Republican Matt Fong is counting on a big crossover vote in November to help him become the next United States senator from California. That vote would be from his mother, March Fong Eu, a veteran Democrat who served as California's secretary of state for 20 years.But it's more than just a family affair. Asian-American Democrats from all over the state flocked to Republican Fong in the June primary, and many are expected to do so again this fall.The heavy crossover vote is an indicator of how Asian-Americans have become energized as a political force in 1998, and how they are rewriting the norms of minority politics in the US.While African- Americans and Latinos have become overwhelmingly committed to one party, the Democrats, Asian-Americans are emerging as a minority group still up for grabs in a political sense. They are not closely wedded to either party and are more than willing to cross party lines for a deeply felt issue or preferred candidate.Joined with that fluidity are surging ethnic pride, born in part from perceived slights during the Asian campaign-finance scandal of a few years ago, and the simple fact that their numbers and experience are reaching critical mass in areas where they have the greatest concentration."It's a population in the making, in a political sense," says Paul Ong of the Lewis Center for Regional Policy Studies at UCLA. "It's very unlike other minority groups. There is no strong party affiliation and even when there is, party affiliation does not predict voting patterns."Analysts are divided on whether Asian- Americans will commit more to any party over time. But as their numbers rise and the major parties scramble for new members among the nation's rapidly growing nonwhite population, their political leverage is likely to increase.That dynamic is already under way in California, destination for one-third of the country's new immigrants each year and home to twice as many Asian-Americans as any other state.Party affiliation in California clearly distinguishes Asian- Americans from other minority groups. African-Americans are registered Democrats by a ratio of about 8 to 1 over Republicans. Latino Democrats outnumber Republicans by 2 to 1. But Asian-Americans tilt only slightly toward the Democratic Party, and a high proportion, 20 percent, decline to state any party affiliation.History best explains why Asian-Americans' political orientation differs from other minorities'. African-Americans used the political process to empower themselves during the civil rights era. …