elaine kamarck, senior fellow at brkinis initute, ss it would be historic for supeelegates to vote against the pe in their ate. aiai karck sot: they'v'vbebe at conventionsnsincece the 19 conventnt they y nener overturned the will of the people. vo: : marcrcys on ththfirst ballot at the convention, most deletes ick to the decisio of their states. if tre is no clear winner afafr the firsballll, , eyeyre free to ooho theli. . kakarck says s se republjcan superdelegates h he been outsken against d ld trump, , and d y thth will never susuort the e p trunr.r. elai kamar s: the pesele gegeto dece rstvtvutut thop are undecidedthen the partrtleadadshsh sps in. we haven't seethat hapap in the modern age,e,ut it ul happenand thth year, side, , o knkns, this c cld happen.@.( vo: in some prarieelegate diststbuon has been sleadidi. for exenpl bernie sanders won w hampshshe picking up 15 delegates to hillary intos nine. the catc clton is currently backed by six supepeelegegesn thththate, while sders is cked by one, , king it near tie.` elelne k karar sot: if something happpped and bernisanders started d`

. >> reporter: author and brookings institution scholar elaine kamarck has been on the democratic party's rules committee for almost 20 years. >> so we tell the states exactly how many delegates they can have and how many delegates each congressional district can have in the state. we tell the states how they have to allocate delegates to presidential candidates. there's a lot of central control from washington on the democratic state parties. >> reporter: democrats require every state to award delegates proportionally, in a percentage that more or less reflects their primary vote total. they've long banned the "winner- take all" approach. republicans, by contrast, take a more "federalist" approach. >> the theory behind the republican delegate selection process is that each state has a great deal of authority and autonomy in choosing its own method. >> reporter: ben ginsberg is former general counsel of the republican national committee and was an election lawyer for the campaigns of george w. bush and mitt romney. he says this year's rules are a mixed bag of proportional and winner-take-