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Top Obama campaign adviser David Axelrod on Sunday defended Democrats’ lawsuit challenging an Ohio law on early voting for U.S. service members and called Mitt Romney’s portrayal of the case “shameful.”

The Obama campaign and the Democratic National Committee filed the suit to block a new state law allowing men and women in uniform to vote up until the Monday right before an election, while the cutoff on early voting for the rest of the public is three days earlier.

“The way Gov. Romney stated [the situation] is completely false,” Axelrod said on “Fox News Sunday.” “It’s shameful that Gov. Romney would hide behind our service men and women.”

Axelrod’s comments were the most recent in a back-and-forth since the suit was filed last month in a federal court in the battleground state of Ohio.

“President Obama's lawsuit claiming it is unconstitutional for Ohio to allow servicemen and women extended early voting privileges during the state's early voting period is an outrage,” Romney said Saturday.

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    The Obama campaign responded within hours to Romney’s comments Saturday, saying, "Mitt Romney and his campaign have completely fabricated a claim that the Obama campaign is trying to restrict military voting in Ohio.”

    Obama campaign officials said the suit doesn’t attempt to restrict the voting rights of military members. The officials said they filed the suit to try to even the playing field for all Ohio voters by allowing early voting up until Monday for everyone, including members of the military, because they believe a two-tiered, early-voting process is unfair.

    Axelrod repeated that point Sunday and suggested Republicans continue to try to find ways to “keep shrinking” the voting population.

    By Sunday afternoon, Romney campaign general counsel Katie Biber issued a statement saying the campaign disagrees with the premise of the Obama campaign and  DNC's argument that providing military voters and their families extra days to vote is “arbitrary” and unconstitutional.

    The National Guard Association and other military groups said earlier that it's "offensive" for Democrats to suggest in the suit that it's arbitrary for service members to get special consideration.

    "This lawsuit is not about us," Biber added. "Last week, respected military groups intervened in the Obama campaign’s lawsuit. They argue that it is absolutely constitutional to give military voters special flexibility in voting, and that it is offensive for the commander-in-chief’s political campaign to argue otherwise. ... We agree with these military groups."

    Men and women in uniform typically get more time than other voters to send in absentee ballots since they may be serving in an overseas or domestic location that is not close to their home polling station.

    The stakes in this legal battle are huge: Obama is anxious to keep Ohio's 18 electoral votes in the Democratic column this November. And no Republican has won the White House without carrying the state.