BY CASEY WOODS AND ANDRES VIGLUCCI

Eduardo Zambrano, an Ecuadorean immigrant, has a green card, a candidate he supports in this presidential election -- Hillary Clinton -- and detailed knowledge of her experience as first lady.

The one thing he doesn't have, despite years of trying: the right to vote.

Zambrano, a legal permanent U.S. resident, applied for citizenship more than two years ago, but a large backlog of naturalization applications at U.S. Citizenship and Immigration Service may lock him out of the November election.

He has now joined growing numbers of prospective U.S. citizens who are suing the immigration service, which under federal law is supposed to respond to naturalization petitions within 120 days of an applicant's interview. Zambrano passed his in June 2006.

''One of the first things I want to do as a citizen is vote, because I want a better world for my children,'' said Zambrano, 38, who is passionately against the Iraq war. ``There are thousands of people like me, and if we can vote, we will change the elections.''

The naturalization delays have become a hot-button topic in immigrant communities across the country at a time when presidential primaries have inspired a surge in voting by immigrants generally and Hispanics in particular.

Immigrant and civil-rights groups say the delays will unfairly deny the ability to cast a presidential ballot to tens of thousands of immigrants who qualify for citizenship. Organizations ranging from the Florida Immigrant Advocacy Center to the Puerto Rican Legal Defense Fund, as well as numerous individuals, have filed lawsuits demanding speedy resolution of long-pending cases like Zambrano's. One Miami attorney, Stephen Bander, has filed 80 suits on behalf of affected applicants -- the immigration agency has resolved all but four.

Zambrano, who lives in Miami, believes the delays are intentional. His lawsuit, filed last week in federal court in Miami, alleges that the current Republican administration is deliberately preventing thousands of potential new voters -- most of them Hispanics that polls say are likely to register as Democrats -- from voting in November.

''This is discrimination, because if the government wanted, it could end the backlog quickly,'' said Zambrano's lawyer, Alfonso Oviedo, who is president of the Miami immigrant advocacy organization American Fraternity.

Ana Santiago, a USCIS spokeswoman in Miami, while declining to comment on Zambrano's case, called any allegation that delays are deliberate ``absurd.''

Immigration officials acknowledged the problems, blaming in part antiquated technology, insufficient staff and a surge in applications last year. The lag in deciding naturalization cases ballooned to an average of 18 months after more than 460,000 immigrants applied for citizenship in advance of a steep hike in processing fees.

But the main holdup in many long-delayed cases appears to be controversial and time-consuming security ''name checks'' instituted by the agency after 9/11.

U.S. officials say the measure, which is performed by the FBI after an applicant has already passed background checks and fulfilled all requirements for citizenship, can require a hand search of paper records at 265 locations. The procedure requires the FBI to determine whether an applicant's name, or a similar name or fraction of a name, has ever appeared in any agency case file at any time for any reason.

Immigration officials say abut 180,000 citizenship applicants have been awaiting name check clearances for more than six months.

Critics -- including the immigration agency's ombudsman -- contend the name checks contribute little to national security while wasting government resources and imposing undue hardship on immigrants.

Last week, USCIS and the FBI issued a statement pledging to address long-pending cases rapidly while reducing most waits for name checks to 30 days. By increasing staff and resources and applying new procedures, the agencies say they will process all name checks pending more than three years by May, all checks pending more than two years by July and all checks pending more than a year by November.

USCIS is spending $15 million to clear the name check backlogs, Santiago said. The joint plan would eliminate the name check backlog by next February -- but that's too late for thousands to vote this year, advocates note.

And many are skeptical that USCIS can meet its goal.

''They have announced plans over the last number of years to eliminate the backlogs,'' said Foster Maer, staff lawyer in Puerto Rican Legal Defense Fund's New York office. ``They've gotten worse, not better.''

The joint statement, for instance, says name checks pending more than four years have been ''eliminated.'' But Mary Gundrum, an attorney at Florida Immigrant Advocacy Center, which has sued on behalf of 25 Muslim immigrants, said one of her clients is still waiting for a name check result after six years.

''Promises, promises,'' said FIAC executive director Cheryl Little. ``If they do what they promise to do within these time frames, that would be a very good thing. But there is no guarantee they will.''