Rep. Shelley Moore Capitio (R-W.Va.), the GOP's best hope of defeating West Virginia Gov. Joe ManchinJoe ManchinConvicted ex-coal exec appeals case to Supreme Court Sanders, Democrats introduce minimum wage bill Overnight Energy: Trump energy nominees face Congress | OPEC to extend production cuts MORE (D) in November's special Senate election, said Wednesday she has decided against getting in the race.

"I looked at this very seriously," Capito said in a radio interview with West Virginia's Metro News. "At the end of the day, it became a decision I had to feel in my own heart and own gut where I could make the biggest difference."

Capito said the Senate is "a place I would like to be someday," but she intends to remain in the House and will run for reelection in the fall.

Despite questions over whether Capito would be able to use the cash in her House campaign account for a Senate run, she said money didn't play into her decision. "I know how to raise the money," she said. "So that wasn't a factor."

With Capito opting out of the Senate race, Manchin is left with a much easier path to the Senate. He announced Tuesday he'll run for the late Sen. Robert Byrd's (D-W.Va.) seat.

The National Republican Senatorial Committee and state Republicans have said the party intends to field a strong challenger, but had their hopes pinned on Capito.

Republican businessman John Raese, who challenged Byrd in 2006, has said he is considering a run against Manchin in the special election this November.

Asked if Manchin could be beaten this fall, Capito said, "Anybody can be beaten. Look at what happened in Massachusetts."

Capito could decide to run against Manchin in 2012 should the Democrat win November's special election. But she is also expected to explore a bid for governor, which would likely be an easier race if Manchin is in the Senate.

Capito decided not to run even though state lawmakers worked to clear the path for her during last week's special session. The Legislature tacked on an amendment to Manchin's bill to change the state's election code, which was thought to allow Capito to run for the House and Senate simultaneously.

But Capito's camp told The Hill on Tuesday that lawyers were looking into whether it was as clear as intended and were still concerned about a potential legal challenge if Capito filed to run for Senate.

— The article was originally posted at 9:34 a.m. and updated at 10:32 a.m.