U.S. service members stationed overseas in Afghanistan and elsewhere may miss their opportunity to vote in the upcoming presidential election, despite the Pentagon’s efforts to ensure their ballots are counted.

American troops and their families stationed abroad are guaranteed access to the polls this November under mandates included in the Military and Overseas Voter Empowerment (MOVE) Act.

The legislation, passed by Congress in 2009, established so-called voter assistance offices at all U.S. installations across the globe, to help U.S. soldiers, sailors, airmen and Marines have their say in all federal elections.

However, congressional Republicans have hammered the Pentagon for not following through on the requirements outlined in the 2009 legislation, leaving thousands of military personnel unable to cast their vote.