Joni Kay Ernst is an American politician and former military officer serving since 2015 as the junior United States senator from Iowa. A member of the Republican Party, she previously served in the Iowa State Senate from 2011 to 2014 and as auditor of Montgomery County from 2004 to 2011. As Chair of the Senate Republican Policy Committee since 2023, after having been vice chair of the Senate Republican Conference since 2019, Ernst is the fourth-ranking Republican in the Senate.