Before California's Republican governor tried to get tough on illegal immigrants in the 1990s, the state had supported Republican Party candidates in all but two presidential elections since World War II.

California has been a solid Democratic state ever since the attempted crackdown, in part because of a backlash by the growing number of Hispanic voters.

Democrats hope to replicate that success nationally by using the current immigration debate to brand Republicans as anti-immigrant and anti-Hispanic. But Latinos are showing signs they are dissatisfied with both political parties, making these voters pivotal players in the November election as Republicans fight to retain control of Congress.

"If the political parties use immigration as a wedge issue, there might be a very big backlash," said Marcelo Gaete, senior director of programs for the National Association of Latino Elected and Appointed Officials, or NALEO.

"We might become the soccer moms of this election, but we will not become the Willie Hortons," Gaete said.

Former President George H.W. Bush used images of Horton, a convicted murderer who raped a woman while on furlough from a Massachusetts prison, in a 1988 campaign ad designed to scare voters into thinking the Democratic nominee, Massachusetts Governor Michael Dukakis, was soft on crime.

Hispanics are the largest and fastest growing minority group in the U.S., accounting for more than 14 percent of the population and about half the annual growth. But several factors diminish their political clout:

—About four in 10 adult Hispanics are not citizens, which means they are ineligible to vote.

—Hispanics are young, with a median age of 27, compared with 40 for white non-Hispanics. Turnout, in general, has increased among young voters, but they still vote at rates lower than for any other age group.

—Hispanics, as a group, earn less and have fewer years of education that than non-Hispanic whites, two more indicators of low voter turnout.

Hispanics "have bad demographics for voting," said Rodolfo de la Garza, a political science professor at Columbia University.

Still, a NALEO analysis concludes that Hispanic voters can prove critical in competitive Senate races in New Jersey and Washington, and House contests in Connecticut, Illinois, Louisiana, New Mexico, Texas and Washington.

In each state, the number of Hispanics has grown much faster than the non-Hispanic population since the start of the decade.

"There is a sense that they are getting more political power within some states," de la Garza said. "In Texas right now, the Latino vote is important in local elections, but not as much in state elections. In California, they can influence state elections."

Most Hispanics — with the notable exception of Cuban-Americans — traditionally have supported Democrats. But President George W. Bush captured about 40 percent of the Hispanic vote in 2004, the most ever for a Republican presidential candidate.

It's unclear which political party will benefit from Hispanic voters in November.

A poll by the Pew Hispanic Center found that 16 percent of Hispanics support Republicans on immigration, down from 25 percent two years ago. Support for Democrats on the issue fell from 39 percent to 35 percent.

One out of four Hispanics said neither party has the best position on immigration, compared with 7 percent two years ago.

"Whatever risk there is for Republicans in these numbers is mitigated by the fact that Democrats are not making any gains," said Roberto Suro, director of the nonpartisan Pew Hispanic Center.

The poll of 2,000 Hispanic adults was taken June 5 to July 3 and has a margin of sampling error of plus or minus 4 percentage points.

In California in 1994, Republican Governor Pete Wilson won re-election by championing an initiative that would have denied many public services to illegal immigrants. Democrats opposed the measure, which was approved by voters but struck down by the courts.

This year, Republicans across the U.S. are divided on immigration and Democrats have failed to stake out a strong position, said Sergio Bendixon, a Hispanic pollster in Florida.

"The differences are not so clear this time," Bendixon said. "The Democrats have been very careful about their view."

The House passed a bill late last year that would make it a felony for illegal immigrants to be in the U.S. That sparked rallies by Latinos and others protesting for immigrants' rights.

The Senate, backed by the president, passed a bipartisan bill that would increase border security while also providing a path to citizenship for many of the estimated 12 million illegal immigrants.

Democratic National Committee spokesman Luis Miranda accused Republicans of "trying to scapegoat immigrants so they can win elections." But Alex Burgos, a spokesman for the National Republican Campaign Committee, said the Republican Party simply wants "to uphold the rule of law, to protect our border, to oppose an amnesty and at the same time be a nation of legal immigrants."

For many Hispanics, this debate is about their future, Bendixon said, "about whether they are welcome in this country."

The Pew poll found that most Hispanics believe discrimination against them has increased because of the immigration debate.

"The way that immigrants are treated is sort of the proxy for how the Latino community is viewed," said Clarissa Martinez de Castro, state policy director for the National Council of La Raza, the nation's largest Hispanic civil rights group. "When you hear the vitriolic debate on immigration in this country, what do you think of? When you belong to that ethnic group, you feel it."