“I’ve moved three times in the past two years,” he added. “Keeping my voter registration information was not top on my mind because I figured it was all set already.”  Ms. Rodriguez said the commission issued a notice this month encouraging voters to update their registration information before the Oct. 6 cutoff date imposed by many states for new voter registrations. She added that the commission considered issuing a notice this month informing local officials how to handle these voters, but in the end decided not to give poll chal-lengers any ideas on new tactics for singling out voters.  Many of the nation’s highest foreclosure rates are also in crucial swing states like Colorado, Florida, Michigan and Ohio. Because many homeowners in foreclosure are black or poor, and are considered probable Democratic voters in many areas, the issue has begun to have political ramifications. Political parties have long challenged voters with expired registrations, but the possible use of foreclosure lists to remove people from the rolls — though entirely legal — has become a new partisan flashpoint.  Last week, Senator Barack Obama’s campaign filed a lawsuit in federal court, seeking to prohibit the Michigan Republican Party from using foreclosure lists to single out and challenge voters. The state Republican Party has denied having any such plans.  Senator Joseph R. Biden Jr., the Democratic vice-presidential candidate, sent a letter last week along with a dozen other Democratic senators to Attorney General Michael B. Mukasey asking him to ensure that voters facing foreclosure are not harassed or intimidated at polling places.  In Ohio, liberal-leaning groups are planning to help people in foreclosure and families who are homeless to vote by using a five- to seven-day window starting Sept. 30 when state residents are permitted to register and cast an early ballot simultaneously. The Republican Party has filed a lawsuit in state court to block registering and voting on the same day, arguing that state law forbids it.  Asked whether his party planned to use foreclosure information to compile challenge lists, Robert Bennett, a spokesman for the Ohio Republican Party, said the party did not discuss its election strategies in public.  [After this article was published, Mr. Bennett sent an e-mail message adding that the Ohio Republican Party condemns "any effort to challenge the eligibility of voters based on home foreclosures."]  Similar questions were raised two years ago over how to deal with more than a million people who were displaced by Hurricane Katrina. Some of these voters were never found, while others were able to vote with absentee ballots or at satellite locations outside New Orleans.  “Foreclosure victims are distinctly vulnerable because they are not officially recognized as a group needing voting help,” said Robert M. Brandon, president of the Fair Elections Legal Network, a liberal-leaning voting rights group.  Last month, his organization sent letters to the secretaries of state in Arizona, Florida, Missouri and Ohio, asking them to better educate foreclosure victims on their rights. The letters argued that the laws in these states do not bar such voters from voting in their former jurisdictions if their intent is to move back as soon as circumstances allow.  On Wednesday, Jennifer L. Brunner, the Ohio secretary of state who is a Democrat, sent out an advisory to all local officials instructing them what to do if anyone who has lost a home to foreclosure shows up at the polls. If the address listed for such voters is no longer valid, and they moved outside the precinct, Ms. Brunner said, poll workers are instructed to send the voter to the polling place that corresponds to the voter’s new address. The voter will then be given a provisional ballot — special ballots that can be counted only after the voter’s eligibility is verified — at the proper polling place, the directive said.  The state requires that election officials send a notice to all registered voters verifying their address 60 days before an election to check the accuracy of the voter rolls. This month, Ms. Brunner ruled that an undeliverable notice will not be grounds enough on its own for a voter to be removed from the registration lists.  So far, election officials in Indiana, Kentucky, Missouri and Ohio have sent out notices to residents in select counties who have filed for a change of address but who have not updated their voter registration.  But the number of people who have moved, through foreclosure or for any other reason, far exceeds the number of people who have notified their election boards. In Ohio, 375,000 people filed change-of-address forms with the Postal Service, but when state officials sent them cards asking for updated registration information, only 24,000 responded. In Missouri, where 250,000 people notified the Postal Service of their move, only 22,000 told the election board.  Robin Carnahan, the Missouri secretary of state, and a Democrat, said that she is trying to get local election officials to increase the number of poll workers to deal with any confusion or challenges of voters.  In 2004, a Republican Party official challenged a large number of voters at a largely black precinct in Boone County, Mo., causing a backup. Such challenges can cause long lines at polling places if there are not enough poll workers to pull challenged voters out of line, or if the workers have to consult with higher-level election officials for each challenge.  State political parties have traditionally used the mail to determine which voters to challenge. By sending out mailings to voters likely to be of the opposite party, and then seeing which mailings are returned as undeliverable, they know whom to challenge at the polls for not living at their registered address. Using public lists of foreclosed homes, however, can save money by allowing a party to avoid sending out mailings.  William Nowling, a spokesman for the Michigan Republican Party, said that Democratic complaints about foreclosure victims being singled out were baseless.  “We are not using foreclosure lists in any way,” Mr. Nowling said, accusing Democratic groups of engaging in fear-mongering by spreading rumors of such plans. “Our voter integrity efforts are solely designed to fight voter fraud perpetrated by the Democrats, of which there is ample proof and examples, including previous elections where the F.B.I. had to seize and secure ballots in Detroit because ballot boxes were being stuffed.”  A version of this article appears in print on , on Page A18 of the New York edition with the headline: Some Fear Foreclosures Mean Loss Of Vote. Order Reprints| Today's Paper|Subscribe
Officials are struggling to make sure that people who have lost their homes through foreclosure are not disqualified at the polls.