The White House said Wednesday it had mishandled Republican Party-sponsored e-mail accounts used by nearly two dozen presidential aides, resulting in the loss of an undetermined number of e-mails concerning official White House business. Congressional investigators looking into the administration's firing of eight federal prosecutors already had the nongovernmental e-mail accounts in their sights because some White House aides used them to help plan the U.S. attorneys' ouster. Democrats were questioning whether the use of the GOP-provided e-mail accounts was proof that the firings were political.