Herseth Sandlin’s decision is the "elephant in the room," Nesselhuf said. "If Stephanie takes a pass," he said last month, "I think Brendan's got [the Democratic nomination] locked up."
Some South Dakota Democrats privately acknowledge that a primary could effectively kill the party’s chances at winning the general election. The candidates would spend time campaigning against each other, while Rounds--who doesn’t need the name recognition that could come with a primary--can fundraise.
But Rounds could also face a primary challenge. Rep. Kristi Noem, who unseated Herseth Sandlin in the 2010 GOP wave, hasn’t ruled out a Senate run, says a former South Dakota Republican operative. The state’s at-large House seat requires a statewide campaign anyway, and her successful late entry into the 2010 race shows she won’t feel pressure to make a rushed decision, the operative said.
One Democrat suggested that Noem would have trouble passing up an open-seat race, since it might be some time before another opportunity for a promotion opens up. Fellow Republican Sen. John Thune will likely run for reelection in 2016, and GOP Gov. Dennis Daugaard is favored to win his own reelection bid, locking that spot in place until 2018.
For now, though, the focus is on the two Democrats who share a last name. The elder Johnson suffered a brain hemorrhage in 2006, and has said he won't make a decision about whether he'll run in 2014 until this spring.
The GOP will likely use the father-son connection to frame a Brendan Johnson bid, Nesselhuf said, and he urged them to do so. "The Republicans are going to push that this is just Tim Johnson trying to get his son elected,” he said. “I encourage them to continue to think that, because anyone who underestimates Brendan Johnson is going to lose."