Former Secretary of State Hillary Clinton's decision to use a private email server, let alone deleting at least half of the communications on it, was "extraordinary," Washington Post associate editor Bob Woodward said Monday, and the omissions remind him of the decisions made by President Richard Nixon back in the 1970s.

"You've got a massive amount of data," Woodward, the veteran "All the President's Men" journalist told MSNBC's "Morning Joe" program. "It, in a way, reminds me of the Nixon tapes; thousands of hours of secretly recorded conversations that Nixon thought were exclusively his."

Although Clinton initially took the same position, she is now cooperating. Still, Woodward said he expects the investigations to go on for a "long, long time and the answers are probably not going to be pretty."

But ironically, the emails could prove to be a "character study," for good or for bad, about Clinton, he said.

"Is she this secretive, hidden person, or is she this valiant public servant?" Woodward said. "Look at those 60,000 emails, and you're going to get some answers."

He said the FBI, inspectors general and others are "furious" because they have spent hours being trained in the proper use of government email.

There has been a great deal of speculation about the Clinton email server, with many Republicans, including several running for the GOP presidential nomination, calling Clinton a criminal over her use of a private email server. But Woodward said he doesn't think criminal intent is "really the question," but legal jeopardy for her staffers is "also a possibility."

Another issue, Woodward said, is that Clinton is blaming the controversy about her private emails on "dirty politics," but he pointed out that it is President Barack Obama's administration that is investigating her.

Still, nothing has been proven to be illegal, he said, and perhaps it's time to slow down a bit.

"I think in the media and political environment we're in, where everything is driven by impatience and speed, that's going to not be possible," said Woodward, "but they're going to have to get some answers."

Woodward said that the first issue in the matter is "common sense" for people like Clinton or for former CIA Director David Petraeus, who faced legal charges and ended up being fined $100,000 and ordered to be put on probation for sharing classified information with his then-mistress.

"In the world where Petraeus was dealing either as a general or CIA director, or Clinton was dealing as [head of the] State Department, almost everything is classified one way or another," said Woodward, "and you have to have some systems to protect it and you have to use common sense." "How does this work? Easier to describe the creation of the universe. It is — there are literally, everyone, when I was a lieutenant in the United States Navy, in the '60s, I had classification authority. I could say, 'Oh, yes, this is top secret.' So, almost anyone can do it, but there's got to be a common sense approach here ... and the idea of the server and this excuse — Oh, it was all for convenience — isn't going to work."