The Sun report said the Democrat confirmed she will enter the race because the opportunity was too appealing to let pass since Ensign announced his retirement at the end of his term.
She could face Republican Dean Heller, who officially jumped into the race last month. Top state Republican elected officials have rallied around Heller, indicating that a bruising primary fight could hurt the party's chances of retaining the seat.
Ensign is facing a Senate Ethics Committee investigation stemming from an affair with Cynthia Hampton, a former aide's wife in 2009, The aide, Doug Hampton, said Ensign helped him find work as a lobbyist and Ensign's parents gave the Hamptons nearly $100,000.
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