South Dakota Secretary of State Chris Nelson (R) announced Friday that he will challenge Rep. Stephanie Herseth Sandlin (D) for the Mount Rushmore State’s only House seat in 2010.

Nelson’s entry made him the second Republican in as many days to join the race. State Rep. Blake Curd (R) declared his candidacy Thursday. State Rep. Shantel Krebs (R) has also expressed interest in the race.

With his track record of winning statewide elections and the name recognition derived from his position, South Dakota party officials view Nelson as giving them the best shot of defeating Herseth Sandlin, who has comfortably won re-election three times despite the state’s conservative leanings. There is “tremendous grass-roots support for him,— state Republican Party Executive Director Lucas Lentsch said.