Westminster, Calif. — A Vietnamese woman, recently sworn in as a United States citizen in Houston, carried a congratulatory form letter from her congressman to social worker Pauline VanTho.
Impressed, she asked Mrs. VanTho innocently, ''He knows me?''
''Seven years ago when I became a citizen, I didn't get any letters. No one paid attention,'' says Nguyen Xuan Nhut, a social worker with Mrs. VanTho at Houston's US Catholic Conference, a refugee resettlement agency.
The contrasting remarks illustrate two facts:
* The US Indochinese refugee community, whose progressive waves of migration since the 1975 fall of Saigon are showing up again in similar waves of naturalization, is being recognized as a political resource. In their areas of heaviest concentration - like Orange County, Calif., the San Francisco Bay area, and Houston - they are perceived as an emerging voting bloc to be courted.
* Indochinese refugees - mostly Vietnamese - came here for political asylum. But while most have a political conscience, it's the last area of refinement in their American assimilation.
There are 650,000 refugees, and the majority live in California, says Vu-Duc Vuong, a senior consultant to the California state Senate Joint Committee on Refugee Resettle--ment and Immigration. (The US government, though, says California has closer to 36 percent of the refugees.)
At a local level, where ''you can lose by a few hundred votes, if you can get a thousand Indochinese votes, you can swing the vote,'' he adds.
The Vietnamese vote - had those eligible for citizenship voted - would have sent Westminster, Calif., Mayor Kathy Buchoz into a state Senate seat, she says. Though unsuccessful in her bid for the Democratic nomination, Mrs. Buchoz adds that she lost by only 288 votes. Observers agree that she could easily have won more votes than that among her Vietnamese supporters.
Though many could not vote, Vietnamese people in Westminster, a suburb of Los Angeles in sprawling Orange County, raised $10,000 for her campaign last year without being solicited to do so. She inspired their loyalty by opposing a citizen group that wanted to ban the issuance of all new business licenses for refugees, who have a thriving business district in Westminster.
(There are more than 12,000 Indochinese among Westminster's population of 72, 000. More than 50,000 Indochinese, mostly Vietnamese, live in Orange County. It takes five years of US residency to apply for citizenship, plus one or two more years of processing time to become a citizen. Orange County's registrar has no specific data on the refugees who have become citizens or registered to vote.)
''I've seen a progression of more public officials, more elected officials taking an interest'' in the refugee community, says Mrs. Buchoz. ''In the beginning they didn't understand the significance (of resettled Southeast Asians), . . . that they were here and going to stay and get involved. I think there'll be an actual solicitation of (Indochinese) votes next time around.''
Mai Cong McReynolds, a mental health worker with Orange County, says refugees are changing their attitude about living in the US. Just three years ago, many still harbored the idea that they would return to their homeland. As this notion fades, she says, it is being replaced by a desire to sink deeper roots here.
Politicians are realizing that ''100,000 people are not just suddenly going to disappear,'' says Rosa Kwong, an aide to Assemblyman Art Agnos. His efforts, she says, largely have been aimed at educating refugees politically so they can exercise their rights.
It has paid off. The Indochinese community last year held a fund-raiser for him. But, says Ms. Kwong, they are still warming up to the American system. ''These are people coming from a country where giving money to public officials usually was a bribe. It's not a concept they're entirely accustomed to.''
But they do recognize the need to get involved, says Mr. Vuong. ''The sooner we understand the system and participate, the better. One of the keys in this society is politics, and it's a basic sense of self-protection to get involved.'' Refugees have organized on a small scale, he says - from veterans and religious groups to a Vietnamese arm of the Asian Pacific Democratic Caucus, a part of the Democratic Party.
Mrs. Buchoz, who now works as an aide in state Assemblyman Richard Robinson's Garden Grove, Calif., offices, says Indochinese frequently visit to discuss legislation they're interested in. The issues they are most concerned about, she says, are how laws will affect their businesses, education, and immigration. ''They have a tremendous reverence for education, and they can also see that politics will affect their businesses,'' she says.
But few Vietnamese aspire openly to become leaders in their community. One woman was interviewed for this story because she was consistently referred to as a political force in the Vietnamese community. She agreed she is a leader, but begged not to labeled as such because it would give the impression she is seeking power. This first generation distrusts countrymen who aspire to leadership positions, because they associate the loss of their homeland with the leaders and politicians who failed to save Vietnam.
The immigrants have yet to show strong signs of political leanings, though they all share anticommunist sentiments. ''Everyone had to flee the communists at one time or another,'' says Vuong, who adds there is an immediate embrace of Republican anticommu--nist rhetoric among the Indochinese.
The Democratic party has appealed to them in many ways because of its liberal position on social programs. But all observers agree that the new Indochinese-Americans are as likely to side with a Republican as a Democrat in an election if the candidate has shown an interest in their community.