des moines iowa long sometimes arcane ritual elect next u.s. president begin monday 1,100 school church libraries across iowa state wield political influence far great small size year up-close personal evaluation candidates iowans gather neighbor promise cold wintry night kick state-by-state process pick republican democratic nominees nov. presidential election star opening-night role largely rural midwestern state presidential drama four decades old source pride iowa voters spend months evaluate candidates look eye ask question iowans see great privilege great gift take role seriously say tom henderson chairman democratic party polk county home iowa big city des moines caucus begin monday p.m. cst result expect within two three hours gather school community center public locations although least two republican caucus private home one democratic caucus hold equestrian center turnout vary community 1,000 people typically gather cities like des moines dozen less may gather sparsely populate areas state republican democratic party run caucus separately although areas hold different part build republicans 800 caucus sit democrats 1,100. two party also different rule iowa democrats gather group candidate preference public display support tradition allow shift back forth candidate reach threshold support 15 percent voters caucus need consider viable candidates supporters release back another contender lead another round persuasion republicans straightforward write vote privately sheet paper collect count site caucus officials surrogate volunteer campaign may speak neighbor last-ditch plea support add uncertainty go process neither party offer voter turnout estimate year although many iowans predict republicans surpass 121,503 turn 2012. last contest democratic caucus 2008 excitement barack obama candidacy spur record turnout 239,872. iowa 30th populate state tiny new hampshire hold second nominate contest feb. traditionally serve early filter winnow losers elevate top contenders late contest iowa republicans recently spotty record back ultimate presidential nominees neither republican winner 2008 former arkansas governor mike huckabee winner 2012 former u.s. senator rick santorum manage win party nomination iowa democrats back party last two nominees john kerry 2004 obama 2008 ultimately launch obama drive white house edit leslie adler sap sponsor coverage independently produce staff reuters news agency iowa kick 2016 u.s. presidential race caucus tradition