Enlarge By Lorie Jewell, Reuters Gen. David H. Petraeus heads to a Blackhawk helicopter with Barack Obama at Baghdad International Airport July 21. WASHINGTON (AP)  Democrat Barack Obama's presidential campaign is encouraging state elections officials to ensure that all military personnel serving away from home are able to vote, after a Virginia law threatened to toss some absentee ballots aside. Each state has its own rules for absentee voting, often used by troops away on duty. Obama campaign attorney Robert Bauer sent letters to every secretary of state in the country, asking them to take "all steps necessary to make sure that our military voters can vote and that those votes are counted." A 2002 Virginia law aimed at eliminating fraud requires that absentee voters in some cases fill our their ballot with the signature and address of a witness. The registrar in at least one county had said he got dozens of ballots without the witness addresses and would have to cast them aside under the law. Republican presidential candidate John McCain highlighted the issue in press statements, sparking outrage among people who said it would disenfranchise the military. Virginia's attorney general stepped in Monday and said all the ballots must be counted under federal law, which trumps the state law. Federal law does not require the address of a witness to be included. "In at least one state, there has been some question about whether state law limits this federal right," Bauer wrote, in what the campaign said was a reference to Virginia. "There should be no question about this matter." Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more