The poll also found 70 percent of foreign-born Hispanics think they are being held back by discrimination, and half of all Hispanics think the United States has become less welcoming toward immigrants than it was just five years ago.

"More Mexican Amerian Hispanics are seeing discrimination against Hispanics as a major problem," said Mark Hugo Lopez, associate director of the center which conducted the survey.

The results of the survey - which was conducted in English and Spanish among 1,375 native- and foreign-born Hispanics from Aug. 17 through Sept. 19 - come just days before midterm elections in which Hispanics are expected to play an important role, particularly in the Florida gubernatorial and Senate races, and the Nevada Senate contest between Majority Leader Harry M. Reid (D) and tea party favorite Sharron Angle.

Angle has come under fire for running ads in recent weeks that paint Hispanics as menacing interlopers. Angle has denied that her campaign plays on nativist sentiment.

More than half of all Hispanics told Pew pollsters they are worried family members, close friends or they themselves could be deported - a measure of how deeply the issue of undocumented immigration cuts across the 47 million-member U.S. Hispanic community.

Significantly more Hispanics than in past surveys say undocumented immigrants are having a negative effect on Hispanics, a measure of how the issue is simultaneously stirring and dividing the community.

Lopez said the survey did not ask whether Hispanics thought undocumented immigrants were hurting the community by competing for jobs during a recession, or because the backlash against undocumented Hispanic immigrants was affecting the wider community. Even so, more than three-quarters of Hispanics think immigration generally strengthens the United States, and Hispanics appear to be more optimistic about the direction of the economy than the rest of the population.

Most Hispanics - 86 percent - say undocumented immigrants should be offered a path to citizenship once they pass background checks, pay a fine and show proof of employment. Only 13 percent of Hispanics think undocumented immigrants should be deported.

The survey had some good news for Democrats: About 51 percent of Hispanics favor Democratic policies on immigration, while 19 percent favor Republican policies. But previous surveys have also suggested Hispanic enthusiasm and turnout in the midterms will be low. Participation in the election has been dampened by the absence of immigration reform and also because Hispanic turnout typically tends to fall during the midterms.

"We fully expect there will be surprises this fall and those surprises will clearly demonstrate the electoral power of our community," said Rudy Lopez, national field and political director at the advocacy group Center for Community Change, during a recent media briefing about Hispanic voters.

About four-fifths of Hispanics disapprove of Arizona's immigration law and efforts to deny citizenship to the U.S.-born children of undocumented immigrants.

Although immigration generates strong views, Hispanics do not think it is the most pressing issue facing the nation. Along with many other voters, Hispanics rank education, jobs and health care above immigration as pressing concerns.