Posted Oct. 9, 2008 – Tens of thousands of eligible voters in at least six swing states have been removed from the rolls or have been blocked from registering in ways that appear to violate federal law, according to a review of state records and Social Security data by The New York Times.

The actions do not seem to be coordinated by one party or the other, nor do they appear to be the result of election officials intentionally breaking election rules, the paper reports. Instead, the purging is apparently the result of mistakes in the handling of the registrations and voter files as the states tried to comply with a 2002 federal law, intended to overhaul the way elections are run.   Still, because Democrats have been more aggressive at registering new voters this year, according to state election officials, any heightened screening of new applications may affect their party's supporters disproportionately.

The screening and purging of voter registration lists in the six states — Colorado, Indiana, Ohio, Michigan, Nevada and North Carolina — could also result in problems at the polls on Election Day: people who have been removed from the rolls are likely to show up only to be challenged by political party officials or election workers, resulting in confusion, long lines and heated tempers.

Some states allow such voters to cast provisional ballots. But they are often not counted because they require added verification.  Under federal law, election officials are supposed to use the Social Security database to check a registration application only as a last resort, if no record of the applicant is found on state databases, like those for driver's licenses or identification cards. 

In three states — Colorado, Louisiana and Michigan — the number of people purged from the election rolls since Aug. 1 far exceeds the number who may have died or relocated during that period. States may be improperly removing voters who have moved within the state, election experts said, or who are considered inactive because they have failed to vote in two consecutive federal elections.

For example, major voter registration drives have been held this year in Colorado, which has also had a significant population increase since the last presidential election, but the state has recorded a net loss of nearly 100,000 voters from its rolls since 2004. Asked about the appearance of voter law violations, Rosemary E. Rodriguez, the chairwoman of the federal Election Assistance Commission, which oversees elections, said they could present "extremely serious problems."

"The law is pretty clear about how states can use Social Security information to screen registrations and when states can purge their rolls," Ms. Rodriguez said.