WASHINGTON — Tea Party favorite Chris McDaniel and six-term Senator Thad Cochran dueled inconclusively in Mississippi’s primary election Tuesday night, an epic struggle in a party deeply divided along ideological lines. GOP governors in South Dakota, Alabama, and Iowa all coasted to renomination.
Senate hopeful Joni Ernst, a state senator, overwhelmed a fistful of Republican rivals in Iowa after uniting rival wings of the party and will challenge Representative Bruce Braley this fall for a Senate seat long in Democratic hands.
In a third Senate race on the busiest night of the primary season, former governor Mike Rounds won the Republican nomination in South Dakota — and instantly became the favorite to pick up a seat for the GOP in its drive to capture the six the party needs to capture a majority this fall.
Five states picked candidates for governor, including California, where Democrat Jerry Brown cruised to renomination to a fourth term.
Dozens of nomination races for House seats dotted the ballot, including 38 in California’s open primary system, which awarded spots on the November ballot to the two top vote-getters regardless of party.
The marquee contest of the night was in Mississippi, where Cochran, 76, and the 41-year-old McDaniel remained locked in a close, uncallable race as the vote count mounted. Returns from 97 percent of the state’s precincts showed the challenger narrowly ahead — 146,913 to 145,424 — in a three-way race, but just below the 50 percent threshold needed to avoid a June 24 runoff.
Officials said the vote tally did not include provisional ballots, at least some of them cast as a result of the state’s new voter ID law. Those voters have five days to furnish proof of residence. An official canvass could take longer, until June 13.
The contest pits a pillar of the GOP establishment who has helped funnel millions of dollars to his state against a younger state lawmaker who drew backing from Tea Party groups and former Republican vice presidential candidate Sarah Palin. The campaign took a turn toward the sensational when four men, all McDaniel supporters, were arrested and charged with surreptitiously taking photographs of the senator’s 72-year-old wife, who suffers from dementia and has long lived in a nursing home.
One group, ‘‘All Citizens for Mississippi,’’ advertised in two black newspapers on behalf of Cochran and handed out fliers as they appealed to traditionally Democratic voters to extend his career.
Vicksburg Mayor George Flaggs, a black Democrat who served for 26 years in the state Legislature, said he was supporting the white, Republican incumbent. He said the senator has secured federal funding for a US Army Corps of Engineers research station in his city, adding, ‘‘It is incumbent for me to vote for Thad.’’
The race was arguably the year’s last good chance for the Tea Party wing of the party to topple an establishment favorite in a Senate primary, following losses in Texas, North Carolina, Georgia, and Kentucky.
The race, however, is expected to have little effect on the battle for control of the Senate. Former representative Travis Childers captured the nomination to oppose the winner of the Cochran-McDaniel race, but Mississippi last elected a Democratic senator in 1982.
The national stakes were higher in Iowa, where Democratic Senator Tom Harkin’s retirement created an open seat that Democrat Braley, a fourth-term lawmaker, seeks to fill — as does Ernst.
She fashioned her rise in the race on memorable television commercials.
‘‘I grew up on an Iowa farm castrating hogs, so when I get to Washington, I'll know how to cut pork,’’ she said in one of them, concluding with a smile, ‘‘Let’s make ’em squeal.’’ She was able to transcend many of the intra-party divisions that flared in other races, gathering business groups, abortion foes, the Senate Conservatives Fund, and the US Chamber of Commerce — groups not always on the same side in a season of struggle for the GOP
In other Senate races, appointed Democratic Senator John Walsh and Republican Representative Steve Daines in Montana each overpowered primary rivals en route to a likely race in the fall that the GOP is expected to target as another opportunity to gain a seat.
In South Dakota, where Democratic Senator Tim Johnson is retiring, Rounds easily eclipsed his rivals for the GOP nomination. Rick Weiland, making his third try for a seat in Congress, was unopposed by other Democrats.
Democratic Senator Cory Booker had no competition for renomination in New Jersey, and Jeff Bell won the GOP spot on the November ballot.
In New Mexico, former Republican Party chairman Allen Weh won the nomination to oppose Democratic Senator Tom Udall.
California’s open primary law produced a crowded ballot, with incumbent Governor Brown and 14 others competing for primary votes. Republicans included Neel Kashkari, a former Treasury Department official, and Tim Donnelly, a state assemblyman and conservative favorite.
Republican governors winning renomination included Robert Bentley in Alabama, Dennis Daugaard in South Dakota, and Terry Branstad, seeking a sixth term in Iowa. All are favored to return to office in the fall. Governor Susana Martinez had no Republican opposition in her pursuit of a second term in New Mexico.