DENVER—If Democrats were trying to put the calamitous Evie Hudak era behind them on Tuesday night, they didn’t quite succeed. A Democratic Party vacancy committee selected Arvada city councilwoman and Hudak associate Rachel Zenzinger to fill the vacancy left by Hudak’s eleventh-hour resignation last month in the face of a recall threat. Zenzinger’s position on hot-button issues like gun control remains to be seen, but in the short run she’s not going to make anyone forget about Hudak. Zenzinger served as Hudak’s campaign manager in the 2012 election and was reportedly Hudak’s choice for the vacancy. While ProgressNow Colorado praised...