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"I am sorry that this has been confusing to people and has raised a lot of questions," Clinton said of her email flap

Clinton's use of private email has become a major talking point in the campaign

Washington CNN  — 

Hillary Clinton refused to weigh in Friday on whether Vice President Joe Biden will challenge her and run for president, saying he’s clearly “struggling” with the decision.

“I’m not going to address any of the political questions around my friend Joe Biden,” Clinton said in an MSNBC interview with Andrea Mitchell. “He has to make a really difficult decision. You can see him struggling with it, and I just wish the best for him and his family.”

In the wide-ranging interview, Clinton said she intended to give Biden room to make up his mind, and others should do the same.

“If he gets into this race, there’ll be plenty of time to get into the debate and the back and forth, but I think everyone should give him the space and respect he deserves to make what is a very difficult choice for him and his family,” Clinton said.

RELATED: Biden: I ‘would not hesitate’

Clinton is leading most polls but she’s facing big questions about whether the controversy surrounding her private email use at the State Department will hurt her ability to win the White House. Her comments on Biden followed a speech the Vice President gave Thursday in Atlanta, in which he said he “would not hesitate” to launch a campaign if he thought it could be “viable.”

Biden’s son, Beau, died earlier this year and the Vice President was clear that his family was the most important factor in deciding whether to launch a campaign.

“I will be straightforward with you. The most relevant factor in my decision is whether my family and I have the emotional energy to run,” Biden said. “The honest to God answer is I just don’t know.”

The fallout from Clinton’s private email server dominated the interview. The former secretary of state twice declined to outright apologize for using a private email server when she was secretary of state, though she did apologize for any confusion it might have caused.

“I am sorry that this has been confusing to people and has raised a lot of questions,” Clinton said, saying earlier in the interview, “I certainly wish that I had made a different choice and I know why the American people have questions about it and I want to make sure that I answer those questions.”

RELATED: Would Hillary Clinton be this bold today?

Clinton’s use of private email has become a major talking point in the campaign, with Republicans criticizing her as untrustworthy and dishonest and the issue has hurt her in polls. The matter is being investigated by congressional committees and the Justice Department, which is probing whether classified information was transmitted over the private server.

Meanwhile on Friday, Gallup released a new poll that put Clinton at one of her worst favorability ratings in more than 20 years. Americans view Clinton 41% favorably to 51% unfavorably, Gallup found.

She had a 74% favorability rank among Democrats.

Clinton said she realizes now the decision to have a personal — instead of official — email at the State Department was not the right one, but she defended herself as trustworthy.

“My personal email use was fully above board,” Clinton said.

She said she realizes she should have two accounts, but said she’s released all the work-related emails and is looking forward to testifying in public before Congress this fall.

RELATED: Hillary Clinton’s emails: What you need to know

She also said reviews have confirmed “over and over” that she “did not send or receive any material marked classified.”

Emails have retroactively been determined to have classified information in them, but it’s not clear if those emails were known to be classified at the time.

Repeatedly asked why she made the choice to use personal email, Clinton said it wasn’t something she spent much time considering in the moment.

“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, I didn’t really stop and think, what kind of email system will there be?” Clinton said.

Clinton also responded to recent polling that showed Americans associate the terms untrustworthy and liar with her name.

“Well it certainly doesn’t make me feel good, but 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,” she said.

Mitchell also engaged Clinton in a lightning round of questions. One was text or email, which Mitchell acknowledged may not be the most appropriate question.

Laughing, Clinton declared: “Email!”

The Republican National Committee was quick to jump on the interview, saying it showed Clinton’s shortcomings.

“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,” RNC spokesman Michael Short said in a statement. “Hillary Clinton’s repeated distortions of her growing email scandal, which now involves an FBI investigation, and her refusal to apologize only reinforce why three-fifths of the country doesn’t trust her.”