SPRINGFIELD — Despite not being in a contested race in his Southwest Side district, House Speaker Michael J. Madigan was attacked for months by a host of Republican candidates.But days after the election, Madigan is calling the strategy “a failure.”A statement released from “Chairman Madigan and the Democratic Party of Illinois” Wednesday said Republicans lost elections at the statewide level because they focused much of their time and money and him.Madigan’s assessment of Republican …