new york/washington three senior officials democratic national committee resign dnc say tuesday amid shake-up follow hack thousands email embarrass party stag national convention last week resignations dnc chief executive officer amy dacey communications director luis miranda chief financial officer brad marshall announce interim chairwoman donna brazile brazile take role debbie wasserman schultz step last week mention hack give reason resignations statement reorganization cast change look ahead u.s. general election nov. 8. hack dnc email stir discord start party convention philadelphia hillary clinton formally accept party presidential nomination nov. election email publish wikileaks show party officials favor clinton rival nomination u.s. senator bernie sanders primary contest brazile announce transition team say would help position party general election prepare eventual permanent party chair tom mcmahon former executive director dnc lead transition team statement say chief staff brandon davis also continue role oversee dnc general election efforts strategist doug thornell join senior adviser interim basis say democratic party systems also hack fbi investigate cyber attack incident democratic congressional campaign committee dccc computer network use clinton campaign also hack white house decline speculate behind hack democratic party computers refer ongoing investigation federal bureau investigation cybersecurity experts u.s. officials however say believe russia engineer release dnc email influence presidential election clinton blame russia hack russia foreign ministry call accusations insult senior democratic national committee officials resign dnc