WASHINGTON – Counties in 31 states are accepting tens of thousands of electronic absentee ballots from U.S. soldiers and overseas civilians, despite years of warnings from experts that Internet voting is easy prey for hackers.

Some of the states made their technological leaps even after word spread of an October 2010 test of an Internet voting product in Washington, in which a team of University of Michigan computer scientists quickly penetrated the system and directed it to play the school’s fight song. The Michigan team reported that hackers from China and Iran also were on the verge of breaking in.

Election watchdogs, distraught over what they fear is a premature plunge into Internet voting, put most of the blame on an obscure Defense Department unit that beckoned state officials for 20 years, in letters, legislative testimony and at conferences, to consider email voting for more than 1 million troops and civilians living abroad.