Americans for Prosperity, a group backed by the Koch brothers, was heavily involved in the Coralville city council race.  A central issue in Coralville’s elections was the city’s decision to use Tax Increment Financing and borrow millions to develop Iowa River Landing, the location of the Marriott Hotel and Convention Center, Von Maur department store (lured from Iowa City), and Backpocket Brewing (definitely worth a try, regardless of your views on government use of TIF). The city still owns and manages several of the properties.  This quote from the New York Times (before the election), sums up the contention:

Critics complain that the debt has prevented the city from lowering property tax rates. They also complain that the complex rules of tax-increment financing siphon property tax money away from the schools, leading the state to pay $2.5 million toward Coralville schools each year.

But city officials argue that their investments have helped the economy boom — $757 million in retail sales last year, a more than fourfold increase since 1997 — and that the debt will be paid. They blame General Growth for stirring much of the criticism, saying the developer was upset that Von Maur went to the Iowa River Landing and not the mall.

If you read the entire article from the Times, and this article from ABC News (after the election), you see that there was a backlash to the outside spending; enough to propel the incumbents to victory in an election that shattered previous records for voter turnout.