News that indicted Ald. Willie Cochran will plead guilty to corruption charges and not run for re-election shook up the already crowded race for the 20th Ward seat — which has now been held by three politicians convicted of crimes related to their official duties. Two candidates dropped out of the 49th Ward race and endorsed Maria Hadden’s bid to unseat Ald. Joe Moore, while new candidates surfaced in the 15th and 50th wards.