Evan Vucci/Associated Press Democratic presidential candidate Sen. Bernie Sanders (I-Vt.) said last year he was "sick and tired of hearing about [Hillary Clinton's] damn emails."

Democratic presidential candidate Bernie Sanders is still steering clear of directly attacking opponent Hillary Clinton over her email controversy, but said Sunday it's a "serious issue" -- and that his past statement that he was "sick and tired of hearing about [her] damn emails" doesn't mean he thinks she did nothing wrong.

Clinton, a former secretary of state, is under renewed scrutiny for her use of private email during her time at the State Department. The agency announced Friday that it had withheld 22 emails determined to be "top secret" from public release, although at the time they were sent they were not marked as classified.

CNN's Jake Tapper asked Sanders, an independent senator from Vermont, about his memorable "damn emails" remark in an October debate and whether it meant he didn't think Clinton erred in her use of a private email account.

"Nope, nope. That is not, I think, a fair assessment," Sanders replied on CNN's "State of the Union." "That is, I think, a very serious issue. There is a legal process taking place, I do not want to politicize that issue. It is not my style."

He called the controversy "a serious issue" on NBC's "Meet the Press" on Sunday as well, although again he said he wouldn't make personal attacks on Clinton.

"I am not going to attack Hillary Clinton," Sanders told NBC's Chuck Todd. "The American people will have to make that judgment."

The Clinton campaign called on Friday for all of the emails to be released, and said the department deeming 22 of them "top secret" now "appears to be over-classification run amok."

Clinton herself responded to the controversy Sunday on ABC News' "This Week with George Stephanopoulos."

"There is no classified marked information on those emails sent or received by me. ... So I do want them released," she said.

Martin O'Malley, the other Democratic candidate in the race, didn't want to touch the issue of Clinton's emails during a Saturday night campaign event in Des Moines.

"I'm not going to be answering questions about Hillary Clinton's emails," O'Malley told reporters. "I'm leaving that to her and her lawyers."

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