"We'll have to wait and see whether the Iowa Senate flips, but I'd give it probably a 1 in 4 chance." The Cook Political Report changed its rating of Iowa's U.S. Senate race from "likely Republican" to "leans Republican" on June 3. "What typically happens is that people that either belong to, or lean towards a president's party, sometimes they're a little complacent," Cook said. "There's some House races that may skip over a little bit, but we're not seeing as much of that in other states as we are in Iowa, and we'll have to wait and see whether the Iowa Senate (seat) flips." "Really, only 10% of all registered voters are really independents that vote," Cook said.