chicago/palm beach fla. u.s. presidential candidate donald trump cancel campaign rally friday night amid security concern hours republican front-runner earn endorsement former rival say billionaire pugnacious campaign style belie thoughtful private side two different donald trump one see stage one cerebral sit consider things carefully ben carson say friday become second former republican candidate back trump white house race soft-spoken retire neurosurgeon drop race last week say american people would comfort discover trump gentle side thousands protesters show trump rally friday even university illinois chicago along thousands supporters show little indication notice anything candidate combative campaign style university arena turn chaotic scene two war side amped position half hour rally slat begin trump campaign staffer announce postpone safety reason unleash compete chant dump trump want trump throughout pack venue make great decision rally trump tell cnn meet law enforcement make call person want see violence add trump blame protesters create disturbances campaign events say love fest among supporters friday event chicago stand huge number protesters virtually match number trump supporters oppose trump campaign events protesters small albeit vocal minority early day speak public event st. louis missouri trump interrupt repeatedly protesters lead event police security increasingly common occurrence raucous rally mouth get trump shout one protesters lead go back mommy say another protester lead away late endorsement trump follow republican debate miami thursday night trump remain three candidates republican race strike markedly civil tone carson shoot top republican pack last year falter early nominate contest endorsement unlikely dramatically shift republican race give trump boost republican establishment crank attack come days crucial nominate contest battle party presidential candidate nov. election republican primaries hold tuesday five state critical trump cement lead determine whether u.s. senator marco rubio florida ohio governor john kasich whose home state among hold contest tuesday able continue increasingly long-shot candidacies trump near rival race u.s. senator ted cruz texas carson comment friday aim soften trump public image campaign mark demean personal attack opponents harsh comment mexican immigrants call temporarily bar muslims enter country trump controversial campaign lead many republican establishment figure call all-out effort prevent win nomination effort carson say would fracture republican party ensure democratic win november ask carson comment trump say want overanalyze one donald trump certainly somebody else sit read think thinker say trump 69 perhaps people think way see form trump also raise possibility attend next republican debate schedule late month salt lake city enough debate opinion say st. louis trump speech interrupt half-dozen time protesters scuffle trump supporters protesters become frequent protester punch north carolina wednesday trump supporter charge assault officer gentle trump advise tell crowd late add flavor make excite good listen long bore speech carson endorsement trump follow another former candidate new jersey governor chris christie announce back last month next tuesday vote pivotal point candidates chase 1,237 delegate primary contest caucus need win republican nomination trump 459 delegate follow cruz 360 rubio 152 kasich 54 accord associate press primaries florida ohio tuesday potential game-changers state award republican delegate winner-take-all basis mean winner popular vote state award state entire slate delegate many state award delegate proportionate popular vote part rubio say round television interview friday still position win florida next week voters home state want trump republican nominee support say want donald trump nominee vote john kasich ted cruz florida vote donald trump rubio say abc good morning america rubio say late supporters ohio vote kasich next tuesday look like best anti-trump tactic clearly john kasich good chance win ohio voter ohio conclude vote john kasich give us best chance stop donald trump anticipate rubio tell reporters event west palm beach florida additional report clarece polke eric beech amanda becker susan heavey washington jon herskovitz texas write john whitesides amanda becker edit frances kerry leslie adler article fund part sap independently create reuters editorial staff sap editorial involvement creation production trump snag former rival 's back scrap chicago rally