But officials in both parties agree that the surge of GOP departures will make the Republicans' challenge more difficult in the Senate. “Any time you lose an incumbent, it’s bad news,” said Republican strategist Rick Tyler, who briefly worked for failed Missouri Senate candidate Todd Akin nearly a decade ago. Several Missouri Republicans are expected to seek the nomination to replace Blunt, but none will be more divisive than former Gov. Two leading Missouri Democrats, former Sen. Claire McCaskill and 2016 Senate candidate Jason Kander, both said they would not run for the open seat. The former president won by the same margin in Iowa, where 87-year-old Republican Sen. Chuck Grassley is considering retirement.