She added that Democrats are closely eying Massachusetts Sen. Scott Brown's seat, but so far no top Democratic challenger has come forward.
Murray also highlighted the candidacies of former DNC Chairman Tim Kaine, now a Virginia Senate candidate, Rep. Chris Murphy (D-Conn.), who faces a competitive primary against Secretary of State Susan Bysiewicz, and Rep. Martin Heinrich (D-N.M.) in New Mexico.
While she endorsed Berkley's campaign, she wouldn't do the same for Heinrich, even though he isn't currently facing a Democratic challenger. But she said it was still early in the cycle, and showered him with praise.
"In New Mexico, Congressman Heinrich's decision to enter the race really confirms that Democrats have a very strong field, and he's doing a great job," said Murray.