WASHINGTON - Rep. Stephanie Herseth Sandlin, D-S.D., has decided to endorse Sen. Barack Obama for the Democratic presidential nomination.

Herseth Sandlin originally endorsed Democrat John Edwards, saying he had the best positions on rural issues. But in the wake of his departure from the race last month, Herseth Sandlin says she has become convinced Obama "will be a president who capitalizes on what South Dakota's communities, families and entrepreneurs have to offer."

She joins the state's other Democrats in supporting the Illinois senator - Sen. Tim Johnson and former Democratic Sen. Tom Daschle have also endorsed Obama. All three are Democratic superdelegates, or political insiders who can cast a ballot for the candidate of their choice at the parties' national conventions this summer.

Herseth Sandlin said her decision was based primarily on Obama's interest in promoting renewable energies and his interest in talking to her in detail about those issues.

"I just like what he stands for in terms of renewable energy primarily, and also his recognition that people have to come together to get things done," she told The Associated Press Tuesday.

She said she also appreciates his appeal to unite the country.

"Like many Americans and many South Dakotans, I have been inspired by Sen. Obama's commitment to finding common ground, and his ability to generate a groundswell of hope and optimism among people of all ages, and of all political stripes," she said.

Obama is in a competitive race against New York Sen. Hillary Clinton for the nomination. Both sides are aggressively courting superdelegates like Herseth Sandlin as they are trying to line up supporters.

Herseth Sandlin said she did not talk to Clinton personally but had a long, detailed conversation with Obama. In addition to renewable energies, she talked to him about forest and American Indian issues, she said.

"I just felt more comfortable with where Sen. Obama has been and where he will continue to be in promoting rural America," she said. "I appreciate the open-mindedness and his sincere desire to have my ideas heard throughout the upcoming weeks and months … that speaks to why so many find him so appealing."

In a statement released by Herseth Sandlin's office, Obama said he is looking forward to working with the South Dakota Democrat "to refocus our energy policy in a way that reduces our dependence on foreign oil, enhances our national security, and creates jobs in South Dakota and across rural America."