Nearly a dozen African American ministers and civil rights leaders walked into the Duval County election office here, television cameras in tow, with a list of questions: How come there were not more early voting sites closer to black neighborhoods? How come so many blacks were not being allowed to redo incomplete voter registrations? Who was deciding all this?

Standing across the office counter under a banner that read "Partners in Democracy" was the man who made those decisions, election chief Dick Carlberg. Visibly angry, the Republican explained why he decided the way he had: "We call it the law."

Black leaders said the scene at the supervisor's office last week was reminiscent of a blocked schoolhouse door at the height of desegregation. They charge that GOP officials are deliberately using the law to keep black people off the rolls and hinder them from voting.

Four years ago, ballots cast from black neighborhoods throughout Florida were four times as likely to go uncounted as those from white neighborhoods. Nowhere was the disparity more apparent than in Duval County, where 42 percent of 27,000 ballots thrown out came from four heavily Democratic black precincts.

Despite attempts by Florida officials to prevent a repeat of the controversy that dogged the last presidential election, black leaders said they are concerned that this year new registrations are being rejected for technical errors and that limited accessibility to early polling places could lead to more disputes, roiling Florida and the nation long after Election Day.

Florida, with 27 electoral votes, is again a hotly contested battleground. Democratic organizations, black churches and civil rights groups have embarked on an aggressive get-out-the-vote effort in minority neighborhoods in Duval County and elsewhere in the state.

From the 2000 election to August 2004, nearly 200,000 black voters were added to the rolls in Florida, a 21 percent increase in large part because of registration drives by groups including America Coming Together. Registration by white voters increased almost 6 percent.

Black people overwhelmingly vote Democratic, and Sen. John F. Kerry (D-Mass.) has made turning out that vote a key part of his Florida strategy. He and his running mate, Sen. John Edwards (N.C.), have made three campaign trips to Jacksonville alone.

But black leaders said they are worried that the campaigning will not matter if black voters are disenfranchised.

In Duval County, 31,155 black voters had been added to the rolls by the end of last week. That is more than the total number of ballots nullified here four years ago, in a race that George W. Bush won by 537 votes.

But hundreds more could show up at the polls only to find they cannot vote. The office has flagged 1,448 registrations as incomplete, and as of last week had yet to process 11,500 more.

A Washington Post analysis found nearly three times the number of flagged Democratic registrations as Republican. Broken down by race, no group had more flagged registrations than blacks.

This, in a heavily GOP county where records show that the number of blacks added to the rolls since 2000 approximately equals the number of non-Hispanic whites.

Some registrations were missing critical information, such as a signature. Others had different problems, with some people listing post office boxes instead of street addresses or putting street addresses on the wrong line.

Secretary of State Glenda E. Hood, a Republican appointed by Gov. Jeb Bush, the president's brother, recently ruled that for registrations to be deemed complete, new voters must not only sign an oath attesting to their citizenship, but also check a box that states the same. Unlike many counties, which have chosen to ignore the directive, Duval County chose to enforce it.

Carlberg, who is acting election chief because his superior is ill, told the ministers that the office did the best it could to contact applicants who submitted incomplete forms, but the law says that "if they aren't complete now, they're not going into the system."

Carlberg's office, as well as Hood's, said the real blame belongs with the Democratic-leaning groups that targeted minority voters and then turned in sloppy and incomplete registrations. The disproportionate number of black Democratic registrations flagged, said Carlberg spokeswoman Erin Moody, is a function of "who those groups are targeting."

But during the 10-minute confrontation at Carlberg's office last week, the ministers argued that the election official had stalled in processing new registrations until it was too late to fix them by the Oct. 4 cutoff. "You kept them in a box in a cage," charged Edward Exson of the Southern Christian Leadership Conference.

The 2000 election sent a record number of black people to the polls in Florida. But these new, inexperienced voters were more likely than their white counterparts to live in areas with outdated, error-prone machinery that did not give voters a chance to correct problems.

In Duval County, the situation was compounded by the election office putting out instructions reminding people to "vote all pages," which led to thousands of invalidated "overvotes" because the list of presidential candidates was spread over two pages.

Since then, the outdated machinery has been replaced, but suspicions linger.

"The big question is: Will our vote count?" Deborah Hargrove, 53, told Susan Hunter, a canvasser for America Coming Together who knocked on her door last week. "Who's to know if they are just going to throw it away in the garbage can?"

But as Hunter handed out fliers to voters such as Hargrove detailing their rights, she also encountered a fierce determination. Many of the retirees in this neighborhood remember when blacks were attacked by white men armed with axes and bats after they tried in 1960 to sit at Jacksonville's whites-only lunch counters in what became known as Ax Handle Saturday.

"I'm gonna vote as long as I live," Sally Brown, 73, vowed when Hunter knocked on her door. "They're not going to make me stop."

One of the major changes enacted since 2000 is aimed at making voting easier by requiring local election officials to allow voters to cast ballots up to 15 days before the election. The law does not specify how many early voting sites there must be.

The ministers who went to Carlberg's office last week had plans to bus their congregations to those sites after Sunday services this month as a way to help those juggling jobs or without a car.

Orange County, which has approximately the same number of registered voters as Duval, has opted to open nine early voting locations. Duval will have one, even though Jacksonville is geographically the largest U.S. city, covering 840 square miles. It will be at Carlberg's office, miles from most of the majority black precincts. The same is true in Volusia County, where the GOP supervisor has angered black ministers there by refusing to open the site on Sundays.

Carlberg would not detail his reasoning with the ministers when they gathered at his office last week.

Afterward, the Rev. James Sampson, president of the Baptist Ministerial Conference in Duval, declared that "the spirit of George Wallace" is "alive and well."

Carlberg noted that the black leaders arrived unannounced with a contingent of reporters and refused his invitation to meet privately. "It should have been conducted in a nonmedia environment," he said in an interview. "Someplace where we could sit down and discuss the issues in a gentlemanly, civilized fashion."

In a follow-up letter to the ministers, Carlberg said that additional sites cannot be added this close to the election. The office does not have time to train staff or install equipment, he said.

But in Volusia County, which has been sued in federal court over the same issue by the NAACP, spokeswoman Deanie Lowe said the election office is looking into adding three sites.

Others complain that while election officials here have been slow to process new registrations and are doing little when it comes to early voting, they have been quick to send out letters informing felons that they have lost their right to vote.

Florida is one of seven states, including Virginia, that bar felons from voting if they fail to appeal. Studies show that the laws disproportionately disenfranchise black men.

Earlier this year, Hood's office developed a list to help supervisors purge felons from the rolls. A similar 2000 list disenfranchised eligible voters, and media organizations sued to make this year's list public. Local newspapers found that it included the names of 2,000 felons whose rights had been restored, many of them black, and did not identify ineligible Hispanics, who lean Republican.

Hood's office was forced to abandon the list, leaving each county to decide how to purge felons from the voting rolls. Carlberg's office purges an average of 140 felons a month.

Michael D. Frederick, 38, showed Hunter the letter he received from Carlberg's office after a felony battery conviction, along with his tattered voter registration card.

"They couldn't wait to send this to me," he said. "I voted every election -- city council, schools, didn't matter. I'm undereducated, and I'm black, but now this, this is my third strike. I kept it as a reminder that they finally took my voice away."

Staff writer Dan Keating in Washington contributed to this report.

Duval County election official Dick Carlberg, left, listens to ministers and civil rights leaders, who question whether blacks are being fairly treated.