It looks like the battle by six-term incumbent Thad Cochran to hold on to his Senate seat in Mississippi won’t be getting easier any time soon. The Republican faced a formidable challenge from Tea Party state senator Chris McDaniel in Tuesday’s primary, which experts say will likely necessitate a runoff. Neither candidate appears to have secured more than 50 percent of the vote because a third candidate, Thomas Carey, has earned about 2 percent. Other primaries throughout the country had clearer outcomes. Pig castrator and state senator Joni Ernst won the GOP primary in Iowa. In South Dakota, former Gov. Mike Rounds won the Republican nomination and, unsurprisingly, Gov. Jerry Brown of California won the Democratic nomination for governor.