. ▁ ▁He ▁represented ▁a ▁" left ▁opposition " ▁within ▁the ▁party , ▁and ▁accused ▁its ▁more ▁conserv ative ▁leadership ▁of ▁being ▁in effect ive ▁against ▁Rob lin ' s ▁cent rist / progress ive ▁government . ▁ ▁He ▁was ▁defeated ▁by ▁establishment ▁candidate ▁G ild as ▁Mol gat ▁by ▁ 4 7 5 ▁votes ▁to ▁ 2 7 9 ▁on ▁April ▁ 2 0 , ▁ 1 9 6 1 , ▁one ▁day ▁after ▁the ▁party ▁formally ▁renamed ▁itself ▁the ▁Man it oba ▁Liberal ▁Party . ▁ ▁Res ignation ▁Roberts ▁res igned ▁from ▁the ▁legisl ature ▁to ▁contest ▁the ▁ 1 9 6 2 ▁federal ▁election ▁in ▁the ▁r iding ▁of ▁Pro ven cher ; ▁he ▁was ▁defeated ▁by ▁Progress ive ▁Conserv ative ▁Warner ▁J org enson ▁by ▁about ▁a ▁thousand ▁votes . ▁ ▁He ▁again ▁lost ▁to ▁J org enson ▁in ▁the ▁ 1 9 6 3 ▁federal ▁election , ▁by ▁a ▁slightly ▁greater ▁margin . ▁ ▁Roberts ▁subsequently ▁worked ▁as ▁a ▁Man it oba ▁ad visor ▁to ▁Liberal ▁Prime ▁Minister ▁L ester ▁B . ▁Pear son , ▁and ▁served ▁as ▁president ▁and ▁acting ▁leader ▁of ▁the ▁Man it oba ▁Liberal ▁Party ▁from ▁ 1 9 6 9 ▁to ▁ 1 9 7 0 ▁( after ▁party ▁leader ▁Robert ▁B end ▁failed ▁to ▁win ▁his ▁seat ▁in ▁the ▁ 1 9 6 9 ▁provincial ▁election ). ▁ ▁He ▁also ▁worked ▁as ▁an ▁executive ▁officer ▁for ▁McC abe ▁Gra in ▁Company ▁Limited , ▁later ▁National ▁Gra in ▁Company ▁Limited . ▁In ▁