backers democratic presidential contender bernie sanders launch campaign win rival hillary clinton prize supporters superdelegates make difference tight race party nomination email phone message petition send sanders boosters backfire upset superdelegates aggressive tone lead many dig heel clinton accord interview conduct reuters drive flip clinton super delegate sanction sanders campaign spokesman michael briggs say bernie campaign focus reach voters earn delegate primaries caucus say statement stress sanders campaign coordinate supporters contact superdelegates however unofficial push could complicate u.s. senator vermont efforts woo critical bloc come months effort time take angry tone message review reuters show reflect anti-establishment tinge 2016 presidential race many voters unhappy washington insiders 85 percent 4,763 delegate vote democratic national convention decide face republican rival november election determine result state nominate contest remain 15 percent hold superdelegates get vote however like mean could hold key tight contest superdelegates make party leaders elect senators members congress governors democratic party adopt system early 1980s way give party leaders control nominate process though yet play decisive role nomination idea get people long view ... arguably best interest party heart say terri fine professor political science university central florida least one superdelegate back sanders however find system overturn regular voters flaw superdelegate fight end superdelegates say larry cohen former president communications workers america union volunteer full-time sanders campaign among super delegate tip hand far clinton hold 453 20 sanders accord new york time delegate tracker among regular delegate nominate contest clinton lead 91 65 south carolina primary graphic tmsnrt.rs/1qhzcsj republican party reserve slot members national leadership influence democratic superdelegates interview 10 505 super delegate support clinton reuters reach show nine approach people purport back sanders nearly displease tone outreach isabel framer ohio superdelegate clinton example get voice mail last week urge vote sanders accordance people voice mail hear reuters anonymous male caller say think crap get vote whichever way want ... watch vote easily frighten framer tell reuters go change vote threats akilah ensley north carolina superdelegate say start hear often sanders supporters name appear wikipedia list note support clinton nice rather abrasive say add attack decisions probably best way change mind luis heredia arizona superdelegate clinton say receive 30 phone call email instant message sanders supporters majority angry tone demand heredia say lacy johnson indiana superdelegate back clinton meanwhile say receive mix message include one say threaten make pay andres ramirez political consultant las vegas nevada superdelegate support clinton say past campaign would typically try soft-sell candidates rather use pressure tactics way go experience never happen say unclear direct call email clinton superdelegates seattle resident justin renquist push outreach although stress contact need civil renquist call part superdelegate task force army rally sanders supporters reach superdelegates via facebook twitter mean 3,000 group slam guy politely nicely ... basically say look system undemocratic renquist say friday group issue statement say support condone engage communication superdelegages vulgar threaten harass intimidate sanders fan meanwhile gather 300,000 signatures least two petition moveon.org ask superdelegates vote line result primaries caucus third petition democracy america site also ask superdelegates follow state nominate contest start robert reich secretary labor bill clinton endorse sanders sanders campaign plan effort win superdelegates possibly april make much strong approach superdelegates say tad devine senior adviser sanders campaign clinton campaign meanwhile start officially court superdelegates months ago proud support democratic party leaders trench say jesse ferguson spokesman clinton campaign edit richard valdmanis tomasz janowski article fund part sap independently create reuters editorial staff sap editorial involvement creation production sanders supporters courtship clinton superdelegates may backfire