Mandel told The Columbus Dispatch he needed more information, expressing skepticism about giving taxpayer dollars to energy companies through loan guarantees. The bankruptcy and ongoing federal investigation into Solyndra, a California solar energy company that secured a half-billion dollars in loan guarantees from the Department of Energy, has fueled concerns about the program.

John Kasich, Ohio's Republican governor, supports the plan for an enrichment plant south of Columbus, as do both of the state's senators, Republican Rob PortmanRobert (Rob) Jones PortmanGOP leader: Congress may settle for pared-down immigration deal Senate Republicans call on Trump to preserve NAFTA Key senator floats new compromise for immigration talks MORE and Democrat Sherrod BrownSherrod Campbell BrownTrump accuses Dems of 'treasonous' behavior Former Ohio football star faces conservative rival in GOP primary fight Dems press Trump for 'Buy American' proposals in infrastructure plan MORE, whose Senate seat Mandel is targeting.

"We're going to reach out to USEC and visit because we want to see how it works, and what benefit this would bring to them and the local community," said Mandel spokesman Joe Aquilino, calling Brown's tenure in the Senate a sad story of failure. "Sherrod Brown is the last person to be lecturing on jobs, since under his last decade representing Ohioans, our state has lost 600,000 jobs." 

Brown faces a difficult reelection in a key battleground state that Republicans see as a major part of their path to take control of the Senate. Brown handily won his last election but has seen his approval ratings slide, along with many incumbents and Democrats in Washington.

Half of Ohio voters in a Quinnipiac University poll released Thursday said Brown deserves another term — an encouraging number for Brown, compared to many incumbents in an unpopular Congress. But Brown risks being dragged down by having President Obama on the ticket in 2012; Fifty-three percent of Ohio voters said they disapprove of Obama's job performance. 

Mandel, a first-term state treasurer, is a relatively new face to Ohio voters, but has attracted heavy attention inside Ohio and out. He has also secured the endorsement of conservative GOP kingmaker Sen. Jim DeMint (R-S.C.).

This post was updated at 2:58 p.m. to add Mandel's response.