Democratic Sen. Tim Johnson’s open seat in South Dakota continues to be the most likely seat to change partisan hands next year. It doesn’t help that his party can’t agree on whether to support the only Democratic candidate in the race.

Johnson probably would have been vulnerable had he decided to seek re-election in 2014. Now that he’s gone, the state is a very good Republican takeover opportunity.

Some Democratic strategists wanted former Rep. Stephanie Herseth Sandlin to run, but she declined. Meanwhile, Rick Weiland is in the race. He has the support of Johnson, former Senate Majority Leader Tom Daschle, and 30 sitting United States senators. But not all Washington, D.C., Democratic strategists are so enthusiastic about Weiland’s prospects.

Former Gov. Mike Rounds is the front-runner for the GOP nomination, but there will be a primary, and Republicans could still see some drama there. But if the Democratic nominee doesn’t have the enthusiastic support of national party operatives and the Democratic Senatorial Campaign Committee, it is very difficult to see how Weiland wins in a state as Republican as South Dakota.

We’re moving the South Dakota Senate race from Lean Republican to Republican Favored in the Rothenberg Political Report/Roll Call ratings.