President Bush's campaign charged yesterday that fraudulent voting engineered by pro-Democratic groups could throw the election to John F. Kerry -- a charge Democrats immediately attacked as a Republican smoke screen to justify the intimidation of minority voters on Election Day.

With less than two weeks until Nov. 2, reports of skullduggery by both Kerry and Bush supporters are flying in key battleground states: a burglary that resulted in the theft of hundreds of completed registration forms in New Mexico; a man paid with crack cocaine to register fictitious voters such as "Mary Poppins" in Ohio; a Colorado resident who registered to vote not once, but 35 times.

In a conference call with reporters yesterday, three top Bush campaign officials cited reports of thousands of phony registrations around the country. Deputy campaign manager Mark Wallace contended that already there is evidence of "an enormous amount of fraud" in the presidential race.

Jack Corrigan, a senior adviser to the Democratic National Committee, called the Republicans' assertions "hysterical, hypocritical and false."

"They're using phony fraud claims to keep voter turnout down and build a smoke screen to challenges to voting rights on Election Day," he said. "We expect better from the president's campaign."

Despite the charges and countercharges, however, many nonpartisan experts said they doubt that suspect registrations will lead to widespread illegal voting in the presidential election.

To a large degree, election officials said, the bad registrations can be attributed to the parties' decision to outsource voter registration operations to private companies and nonprofit groups that pay temporary employees for every new voter they sign up. In essence, they said, the problem is not fraud for partisan gain but greed.

Steven Ansolabehere, a professor of political science at the Massachusetts Institute of Technology and the former director of the Caltech-MIT Voting Technology Project, said the parties would be better off spending the money to properly register supporters and then get them to the polls.

"The ultimate check on that kind of fraud is the difficulty of actually perpetuating it. It takes a lot of effort to register and vote three or four times," he said.

It has not always been that way. In the days when party organizations were strong all the way down to the ward level, voting fraud was common.

Parties are not that organized anymore, and societal norms have changed, Cornell University political scientist Richard Bensel said. But he said he worries that a trend to make absentee voting easier could once again allow parties to buy votes -- in the privacy of someone's own home.

Bush campaign manager Ken Mehlman accused Democratic lawyers yesterday of a "systematic" effort to overturn rules designed to ensure the integrity of the election. But, in Florida, it was the Republicans who pushed earlier this year to eliminate a legal mechanism that had helped prosecutors detect absentee-ballot fraud.

Traditionally, Republicans in Florida have done better with absentee ballots than Democrats. The GOP-controlled legislature there got rid of a requirement that the casting of an absentee ballot be witnessed, a rule that had helped ferret out fraud in the 1997 Miami-Dade County mayoral election, which was eventually overturned.

"It was amazing to me that we as a legislature would vote to make it easier to commit that kind of fraud," said state Rep. Dan Gelber, a Democrat and former federal prosecutor. "They weren't screaming about the fraud problem then."

Democrats charge that all the talk about fraud is designed to provide cover for what is expected to be an aggressive effort on the part of Republicans to challenge the eligibility of Democratic voters at the polls. In New Mexico, for instance, a crime task force was set up by the Republican U.S. attorney to investigate allegations of voter-registration fraud. To date, said New Mexico Secretary of State Rebecca Vigil-Giron, a Democratic member of the task force, "they haven't come up with anything at all."

Some allegations of fraud involve felons voting in states where it is illegal for them to do so, such as Florida and Colorado.

Four years ago in Florida, local newspapers found, felons illegally cast votes in the disputed presidential election. This year, some counties have done little to purge their rolls of felons. For instance, in Miami-Dade, spokesman Seth Kaplan said the last time the rolls there were purged of felons was in May. In Colorado, the Republican secretary of state has come under fire for similar inaction.

Some of the hottest charges this year have involved allegations that groups working to register voters for one party ripped up the registrations turned in by voters not inclined to vote for their candidate.

There are criminal investigations into allegations that workers for a Republican Party-funded company threw out Democratic registrations in Oregon and Nevada. Likewise, there are allegations in Florida that a worker for a Democratic-leaning group ripped up Republican registrations.

But while both parties have seized on these instances, election officials are skeptical. In Clark County, Nev., where a local television station broke one of the stories last week, Democrats unsuccessfully sued to extend the registration deadline for the alleged victims, who were said to number in the hundreds, if not the thousands.

Registrar Larry Lomax said he has not received, as a result of the story, an unusual number of complaints from people who say that they registered but are not on the rolls.

"There's more political rhetoric this year, there's no doubt about that," Lomax said. "But I haven't seen any evidence that substantiates either side's position."