With about 145,000 immigrants eligible to become citizens in San Diego County, the foreign-born population is poised to become an influential voting bloc in the next presidential election, according to a new study released Tuesday.

Moreover, 85,000 children of immigrants in the county will become eligible to vote by 2012, according to the report titled the "Integration Potential of California's Immigrants and their Children."

In some political districts in San Diego County, new immigrant voters could make up 20 percent or more of the electorate by 2012.

The effect of such a shift in the makeup of North County could have an enormous effect on its political representation. The region, which has a large population of new immigrants, is represented by an all-Republican delegation who are among the staunchest opponents of illegal immigration.

North County also has become a flashpoint in the national immigration debate with such efforts as the Escondido City Council's failed ordinance to bar landlords from renting to illegal immigrants.

The study was commissioned by the Grantmakers Concerned with Immigrants and Refugees, a group that promotes immigrants' contributions to the nation and their participation in civic life.

The study culled data from the U.S. Census to calculate how many immigrants live in each county, assembly district and state senate district.

Daranee Petsod, executive director of the Sonoma County-based organization, said the study was important for policy makers.

"We believe that we can't have a vibrant society if we don't integrate immigrants," Petsod said.

Statewide, more than 6.5 million foreign-born residents either are naturalized citizens or are eligible to become naturalized citizens, said Rob Paral, a researcher and the study's author.

In addition to the 6.5 million adult immigrants, there are 1.2 million children of immigrants in California who will be eligible to vote by 2012, Paral said.

The figures in the report may not be surprising to some immigrant rights advocates, who have said that immigrants, by force of their numbers, will change the political landscape of the state and the nation in the near future.

Isabel Alegria, a spokeswoman for the California Immigrant Policy Center, an immigrants rights group based in Los Angeles, said such a huge voting bloc could change the national debate on immigration.

"I doubt that immigrants are going to support anti-immigrant proposals," Alegria said. "I think the message is to representatives is one of inclusion."

Within North County's state assembly and senate districts, new immigrant voters could make up more than 20 percent of voters by 2012, according to the report. For example, the 74th Assembly District, which includes much of North County, has about 69,000 immigrants and their children who would be eligible to vote in the next presidential election, the report says. The 74th District has 250,000 eligible voters.

Other districts in North County could see similar jumps, including a 28 percent increase in the 75th Assembly District, and a 22 percent increase in the 38th Senate District.

The 74th Assembly District is represented by Assemblyman Martin Garrick, R-Carlsbad. He was not available to comment Monday.

Immigrants from Mexico make up the largest group of people from one country, 914,000, who are eligible to become citizens. The second-largest group is from the Philippines, 137,000.

Arcela Nunez-Alvarez, director of the National Latino Research Center at Cal State San Marcos, said the study offers an important glimpse into a segment of the population that is rarely scrutinized.

The information could help local groups refine their efforts to increase participation of noncitizens to become citizens and vote. She said many of those groups are grass-roots organizations that don't have a lot of money and must focus their voter registration and education campaigns where they will do the most good.

"There is a lot of great potential with this report," Nunez-Alvarez said.

The full report is available at www.gcir.org.

Contact staff writer Edward Sifuentes at (760) 740-3511 or esifuentes@nctimes.com.