WASHINGTON -- Former Secretary of State Hillary Rodham Clinton should fully explain her actions involving the use of a private, nongovernment email account when she was the country's top diplomat, U.S. Sen. Dianne Feinstein said on Sunday, becoming the first major Democrat to urge Clinton to share more details of the private account.

Feinstein said the former first lady and New York senator "needs to step up and come out and say exactly what the situation was," adding that from "this point on, the silence is going to hurt her."

Clinton's husband, former President Bill Clinton, also avoided the controversy Sunday morning.

Asked whether his wife was treated fairly, Bill Clinton replied, "I'm not the one to judge that. I have an opinion, but I have a bias."

"I shouldn't be making news on this," he said, in remarks reported on CNN.com.

Hillary Clinton has been criticized for her use of the private email account and whether she complied with federal rules requiring officials to retain their communications. Clinton says that she's turned over all relevant emails -- totalling 55,000 pages -- to the State Department for review.

Last week, the House committee investigating the deadly 2012 attacks in Benghazi, Libya, issued subpoenas for Clinton's emails, and its chairman said Sunday, "We're not entitled to everything. I don't want everything. I just want everything related to Libya and Benghazi."

Republican Rep. Trey Gowdy said "there are gaps of months and months and months" in the emails the committee had previously received. "It's not up to Secretary Clinton to decide what's a public record and what's not."

Clinton is considered the front-runner for the 2016 Democratic presidential nomination, but hasn't entered the race yet. So far, a tweet has been her only comment on the email controversy. She did not address the issue Saturday night during an event in Coral Gables, Florida, for the Clinton Global Initiative University.

One of Clinton's predecessors, former Secretary of State Colin Powell said Sunday that he has retained none of the emails sent from his personal email account during his tenure at the department in the first George W. Bush administration.

"I don't have any to turn over," he said on Sunday. "I did not keep a cache of them. I did not print them off."

Powell added: "A lot of the emails that came out of my personal account went into the State Department system. They were addressed to State Department employees and the State.gov domain. But I don't know if the servers (for) the State Department captured those or not."

Powell said all the emails from his account were unclassified and most were "pretty benign, so I'm not terribly concerned even if they were able to recover them."

Feinstein appeared on NBC's "Meet the Press," Gowdy was on CBS' "Face the Nation," and Powell spoke on ABC's "This Week."