Earlier this month, U.S. Attorney David Iglesias in New Mexico launched a statewide criminal task force to investigate allegations of voter fraud in the upcoming presidential election. The probe came after a sheriff who co-chairs President Bush's campaign in the state's largest county complained about thousands of questionable registrations turned in by Democratic-leaning groups.

"It appears that mischief is afoot and questions are lurking in the shadows," Iglesias told local reporters.

But Democratic Secretary of State Rebecca Vigil-Giron, named to the task force to allay concerns that the probe was politically motivated, said the investigation is unnecessary.

"This is just an attempt to let people know that Big Brother is watching," Vigil-Giron, New Mexico's chief electionsofficial, said in an interview. "It may well be aimed at trying to keep people away from the polls."

The probe is one of several criminal inquiries into alleged voter fraud launched in recent weeks in key presidential battlegrounds, including Ohio and West Virginia, as part of a broader initiative by U.S. Attorney General John D. Ashcroft targeting bogus registrations and other election crimes. The Justice Department has asked U.S. attorneys across the country to meet with local elections officials and launch publicity campaigns aimed at getting people to report irregularities.

The focus on registration problems comes amid a fiercely contested presidential race and at a time when many Democrats are still angry over the 2000 election, in which ballot irregularities in Florida prompted the U.S. Supreme Court to declare the winner. And it puts the Justice Department in the middle of a charged and partisan debate over when aggressive fraud enforcement becomes intimidation.

Justice officials say it is the department's duty to prosecute illegal activities at the polls, and stress that civil rights lawyers are also working to ensure that legitimate voters can cast their ballots without interference. Justice Department spokesman Bryan Sierra said that "the department must strike a proper balance and we cannot be deterred from investigating allegations of criminal voter fraud."

Civil rights advocates and many Democrats, however, complain that the department is putting too much emphasis on investigating new voter registrations in poor and minority communities -- which tend to favor Democrats -- and not enough on ensuring that those voters do not face discrimination at the polls. More attention should be given to potential fraud in the use of absentee ballots, which tend to favor Republicans, the critics say.

They also charge that announcing criminal investigations within weeks of an election -- as was done in New Mexico on Sept. 7 -- is likely to scare legitimate voters away from the polls.

"I'm concerned that the Justice Department is being overtly political," said Nancy Zirkin, deputy director of the Leadership Conference on Civil Rights. "Bells are going off for me because searching for voter fraud has often been a proxy for intimidating voters."

The Justice Department's guidelines say prosecutors "must refrain from any conduct which has the possibility of affecting the election itself."

"A criminal investigation by armed, badged federal agents runs the obvious risk of chilling legitimate voting and campaign activities," the department's manual on elections crime says. "Federal prosecutors and investigators should be extremely careful to not conduct overt investigations during the pre-election period or while the election is underway."

Experts on both sides acknowledge that faulty or bogus voter registrations are a persistent problem. For example, one study found that 5,400 dead people cast votes over a 20-year period in Georgia. But experts question whether the phenomenon is widespread, and elections officials say they are most concerned about absentee ballot fraud.

"The problem is, you don't know if the voter is being coerced, misled or bribed, because it all happens away from public scrutiny," said Denise Lamb, New Mexico's election director.

Still, in recent months, elections officials in swing states have reported thousands of problematic registrations, including addresses that do not exist, duplicate names, the names of deceased voters and names that appear to be copied out of a phone book by the same person. Republicans have pointed to such registrations as evidence of possible widespread election fraud.

"Violations of voter registration laws, registering dead or nonexistent people to vote, creates the opportunity for Democrats to disenfranchise legitimate voters on Election Day, which on any scale is something that should concern all voters," said Republican National Committee spokeswoman Christine Iverson.

Elections officials of both parties, however, say that bad registrations do not necessarily translate into Election Day fraud. New identification laws, as well as signature checks, make ballot-box stuffing extremely difficult, they say.

Gary Stoff, the GOP director of elections in St. Louis, said that registration irregularities experienced there are "not an attempt to commit fraud," but rather the result of greedy workers who get paid for every new voter they sign up or already-registered voters who forget and register again.

In Ohio, Summit County Board of Elections Director Bryan Williams said the local sheriff and the U.S. attorney's office are investigating irregularities in about 1,500 registrations sent to his office, including a batch mailed by the AFL-CIO. But, he said, he sees no evidence that the purpose is to "bloat the ballot box," in part because of the logistical difficulty of signing a fake person up to vote and then finding a body to vote in that name.

The Justice Department points to its success in rooting out vote-buying problems in local elections in Appalachia. Two men were convicted last week of buying votes during a 2002 judicial election in Kentucky, and several West Virginia residents were recently charged in a vote-buying probe by a U.S. attorney in that state.

But many Democrats are suspicious of the prosecutors' motives in the most recent cases -- most of which involve GOP complaints and alleged wrongdoing on behalf of Democratic candidates -- and are uneasy with Ashcroft's role in overseeing such probes. Ashcroft, a former Missouri governor and senator, came under fire during his 2001 confirmation for vetoing bills that would have promoted voter registration in St. Louis, a heavily African American Democratic stronghold.

John Hickey is the executive director of the Missouri Progressive Vote Coalition. The validity of the group's minority voter registration drive has been challenged by a conservative group whose directors have close ties to Ashcroft. "Look at his history," Hickey said. "I think it's chilling that all these old Ashcroft associates are trying to attack voter registrations instead of saying, 'Great, we want everyone to turn out.' "

Justice officials, while not commenting directly on criticism of Ashcroft, said the attorney general's Voting Access and Integrity Initiative, begun in October 2002, is largely a compendium of policies already on the books. In a statement, the department defended its voting rights record, saying that since 2001, it has filed 22 civil rights lawsuits to protect access to the polls, and in November expects to deploy "more voting rights observers than in any other time in recent history" to protect against discrimination. Sierra, the Justice spokesman, also stressed that prosecutors and FBI agents will not be monitoring polling places on Nov. 2.

But civil rights advocates worry that, in the case of criminal investigations such as the one in New Mexico, investigators will have to go door-to-door to question new registrants before balloting. In the 2002 South Dakota elections, state and federal agents questioned hundreds of newly registered Native Americans, a key constituency for Democrats in that state. The probe resulted in charges against one woman, which were subsequently dropped.

"Often there's no real basis for these fraud allegations," said Jonah Goldman of the Lawyers Committee for Civil Rights Under Law. The New Mexico probe was launched in part at the request of Bernalillo County Sheriff Darren White, who chairs the county's Bush-Cheney campaign. The announcement came after a district court judge ruled against plaintiffs in a Republican-led lawsuit that sought at-the-poll identification requirements for new voters registered through drives. As proof that change is needed, the plaintiffs listed a number of questionable registrations in their lawsuit, including one from a 13-year-old. But several women whose registration cards were attached to the lawsuit testified they registered twice by mistake and that no fraud was involved.

Democratic groups have been pushing to register new voters in New Mexico, which Bush lost by 366 votes in 2000. The Democratic Party has testified that changing ID rules would disenfranchise some voters, and spokesman Matt Farrauto called the criminal probe "worrisome."

Iglesias's spokesman, Norman Cairns, said the FBI is investigating "questionable voter registrations." But he added: "Our objective is not in any way to influence this election."

U.S. Attorney David Iglesias of New Mexico began a voter registration probe after a local chair of the Bush-Cheney campaign complained. Civil rights groups say Attorney General John D. Ashcroft's focus on minority registrants is meant to deter likely Democratic voters.