Hillary Rodham Clinton says her use of a private email system at the State Department wasn't the "best choice" and acknowledged she didn't "stop and think" about her email set-up when she became President Barack Obama's secretary of state in 2009.
The Democratic presidential front-runner said in an interview on Friday with NBC News she was immediately confronted by a number of global hotspots after joining the new Obama administration as its top diplomat and didn't think much about her email.
Her use of private email has now become a distraction for her presidential campaign.
"You know, I was not thinking a lot when I got in. There was so much work to be done. We had so many problems around the world," Clinton said.
"I didn't really stop and think what kind of email system will there be?"
But Clinton did not apologise for her decision when asked directly, "Are you sorry?" Instead, she again said she wishes she had "made a different choice" and that she takes responsibility for the decision to use a private email account and server based at her home in suburban New York.
She added it was a choice that should not raise questions about her judgment.
"I am very confident that by the time this campaign has run its course, people will know that what I've been saying is accurate," Clinton said.
Republicans criticied Clinton's unwillingness to apologise for the decision and said it underscored polls which have shown large numbers of people questioning her trustworthiness.
"What's clear is Hillary Clinton regrets that she got caught and is paying a political price, not the fact her secret email server put our national security at risk," said Michael Short, a spokesman for the Republican National Committee.
In the interview, Clinton said, as she has in the past, that she "should have had two accounts, one for personal and one for work-related."
She reiterated that she did not "send or receive any material marked classified. We dealt with classified material on a totally different system. I dealt with it in person."
