. In what would become a pattern, Republican officials and lawmakers in a number of states, including Florida, New Mexico, Pennsylvania and Washington, made accusations of widespread abuse, often involving thousands of votes.

In swing states, including Ohio and Wisconsin, party leaders conducted inquiries to find people who may have voted improperly and prodded officials to act on their findings.

But the party officials and lawmakers were often disappointed. The accusations led to relatively few cases, and a significant number resulted in acquittals.

The Path to Jail

One of those officials was Rick Graber, former chairman of the Wisconsin Republican Party.

“It is a system that invites fraud,” Mr. Graber told reporters in August 2005 outside the house of a Milwaukeean he said had voted twice. “It’s a system that needs to be fixed.”

Along with an effort to identify so-called double voters, the party had also performed a computer crosscheck of voting records from 2004 with a list of felons, turning up several hundred possible violators. The assertions of fraud were turned over to the United States attorney’s office for investigation.

Ms. Prude’s path to jail began after she attended a Democratic rally in Milwaukee featuring the Rev. Al Sharpton in late 2004. Along with hundreds of others, she marched to City Hall and registered to vote. Soon after, she sent in an absentee ballot.

Four years earlier, though, Ms. Prude had been convicted of trying to cash a counterfeit county government check worth $1,254. She was placed on six years’ probation.

Ms. Prude said she believed that she was permitted to vote because she was not in jail or on parole, she testified in court. Told by her probation officer that she could not vote, she said she immediately called City Hall to rescind her vote, a step she was told was not necessary.

“I made a big mistake, like I said, and I truly apologize for it,” Ms. Prude said during her trial in 2005. That vote, though, resulted in a felony conviction and sent her to jail for violating probation.

Of the hundreds of people initially suspected of violations in Milwaukee, 14 — most black, poor, Democratic and first-time voters — ever faced federal charges. United States Attorney Steven M. Biskupic would say only that there was insufficient evidence to bring other cases.

No residents of the house where Mr. Graber made his assertion were charged. Even the 14 proved frustrating for the Justice Department. It won five cases in court.

The evidence that some felons knew they that could not vote consisted simply of a form outlining 20 or more rules that they were given when put on probation and signs at local government offices, testimony shows.

The Wisconsin prosecutors lost every case on double voting. Cynthia C. Alicea, 25, was accused of multiple voting in 2004 because officials found two registration cards in her name. She and others were acquitted after explaining that they had filed a second card and voted just once after a clerk said they had filled out the first card incorrectly.

In other states, some of those charged blamed confusion for their actions. Registration forms almost always require a statement affirming citizenship.

Mr. Ali, 68, who had owned a jewelry store in Tallahassee, got into trouble after a clerk at the motor vehicles office had him complete a registration form that he quickly filled out in line, unaware that it was reserved just for United States citizens.

Even though he never voted, he was deported after living legally in this country for more than 10 years because of his misdemeanor federal criminal conviction.

“We’re foreigners here,” Mr. Ali said in a telephone interview from Lahore, Pakistan, where he lives with his daughter and wife, both United States citizens.

In Alaska, Rogelio Mejorada-Lopez, who manages a gasoline station, had received a voter registration form in the mail. Because he had applied for citizenship, he thought it was permissible to vote, his lawyer said. Now, he may be deported to Mexico after 16 years in the United States. “What I want is for them to leave me alone,” he said in an interview.

Federal prosecutors in Kansas and Missouri successfully prosecuted four people for multiple voting. Several claimed residency in each state and voted twice.

United States attorney’s offices in four other states did turn up instances of fraudulent voting in mostly rural areas. They were in the hard-to-extinguish tradition of vote buying, where local politicians offered $5 to $100 for individuals’ support.

Unease Over New Guidelines

Aside from those cases, nearly all the remaining 26 convictions from 2002 to and 2005 — the Justice Department will not release details about 2006 cases except to say they had 30 more convictions— were won against individuals acting independently, voter records and court documents show.

Previous guidelines had barred federal prosecutions of “isolated acts of individual wrongdoing” that were not part of schemes to corrupt elections. In most cases, prosecutors also had to prove an intent to commit fraud, not just an improper action.

That standard made some federal prosecutors uneasy about proceeding with charges, including David C. Iglesias, who was the United States attorney in New Mexico, and John McKay, the United States attorney in Seattle.

Although both found instances of improper registration or voting, they declined to bring charges, drawing criticism from prominent Republicans in their states. In Mr. Iglesias’s case, the complaints went to Mr. Bush. Both prosecutors were among those removed in December.

In the last year, the Justice Department has installed top prosecutors who may not be so reticent. In four states, the department has named interim or permanent prosecutors who have worked on election cases at Justice Department headquarters or for the Republican Party.

Bradley J. Schlozman has finished a year as interim United States attorney in Missouri, where he filed charges against four people accused of creating fake registration forms for nonexistent people. The forms could likely never be used in voting. The four worked for a left-leaning group, Acorn, and reportedly faked registration cards to justify their wages. The cases were similar to one that Mr. Iglesias had declined to prosecute, saying he saw no intent to influence the outcome of an election.

“The decision to file those indictments was reviewed by Washington,” a spokesman for Mr. Schlozman, Don Ledford, said. “They gave us the go-ahead.”

Sabrina Pacifici and Barclay Walsh contributed research.

Correction: April 14, 2007

A front-page article on Thursday about the scant evidence of voter fraud that has been found since the Bush administration began a crackdown five years ago misstated a court ruling on a 2003 Texas Congressional redistricting law. While the Supreme Court ruled that the Texas Legislature violated the Voting Rights Act in redrawing a southwestern Texas district, the court upheld the other parts of the plan. It did not strike down the law.