But officials in both parties agree that the surge of GOP departures will make the Republicans' challenge more difficult in the Senate. Several Missouri Republicans are expected to seek the nomination to replace Blunt, but none will be more divisive than former Gov. Ahead of Greitens' announcement, some Republicans worried that he could jeopardize the Senate seat if he emerges as the party's nominee. The former president won by the same margin in Iowa, where 87-year-old Republican Sen. Chuck Grassley is considering retirement. AdMeanwhile, Blunt predicted political success for Republicans in Missouri and beyond during a Monday news conference.