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John Bolton's (search) nomination to the United Nations may not seem to have much to do with a proposed base closing in South Dakota, but the state's junior senator is seemingly drawing a connection in order to keep a promise to voters who sent him to Washington.

Ellsworth Air Force Base (search) is home to the B-1 bomber, one of the most powerful weapons in America's military arsenal. But officials at the Pentagon want to close Ellsworth.

Sen. John Thune (search), a self-described loyal Republican, said he's considering using his most powerful weapon — his vote on the U.S. Senate floor — against President Bush's nominee for U.N. ambassador, a notable break with the administration that is tied to his displeasure over the base-closing proposal.

"My loyalty in this particular matter is with the people of South Dakota, always has been, always will be," Thune said.

Thune won his U.S. Senate seat last November in a tight race against former Democratic Sen. Tom Daschle. The victory was aided by the endorsement of Bush.

At campaign time, Daschle was the Senate's top Democrat and a pointed target for the GOP. Thune squeaked out a victory in part because he campaigned on his ability to defend Ellsworth through his connections with party powers, including the president.

Democrats now say Thune doesn't have the status he needs to stop the base from closing.

"Power in Washington matters. Tom Daschle had it. John Thune doesn't," said Steve Hildebrand, a former Daschle staffer.

Local residents say losing Ellsworth would mean losing South Dakota's second largest employer and would create a potential gaping economic wound to the area.

"It'll have a terrible impact on a lot of people," said Rapid City resident Dennis Leonard.

"There's a lot of money coming out of that base here spent in Rapid City," said Hot Springs resident Tammy Kahler.

"It'll take a decade to recover from it," said Ken McElgunn, a member of the Rapid City Area Chamber of Commerce.

Thune said he wants everyone to know Ellsworth trumps everything, including party loyalty.

"I've been supportive of this administration in everything they've been trying to accomplish, but I am very focused right now on what I believe to be the best interests on my state of South Dakota," he said.

The senator said he has decided to vote against Bolton, but insists that the decision is not a form of retaliation.

"Some people want to attach different motives to that, but the truth of the matter is I don't think he's the best person for the job," Thune said.

The job at hand for Thune is to slow down the base-closing process, if not get Ellsworth off the cut list.

Click in the box near the top of the story to watch a report by FOX News' Steve Brown.