By Arun Kumar 

Washington, Sep 5 (IANS): Democratic presidential frontrunner Hillary Clinton has taken a swipe at her Republican rival Donald Trump, calling his candidacy "a bad development for our American political system."

Trump's bravado could have dangerous repercussions if he became president, the former secretary of state said in an interview with NBC News Friday.

"Loose talk, threats, insults -- they have consequences," she said. "The president of the United States needs to be careful about what he or she says."

Trump is "great at innuendo and conspiracy theories and really defaming people," Clinton said when asked about the real estate mogul's attacks on her long time Indian-American aide Huma Abedin.

Trump recently suggested Abedin, daughter of an Indian father and a Pakistani mother, leaked classified information to her husband, former New York congressman Anthony Weiner, whom Trump called a "perv" and a "sleazebag."

"His campaign is all about who he is against, whether it's immigrants or women broadcasters or aides of other candidates," Clinton said.

"He can unfortunately do what he's doing, which I think is a bad development for our American political system," she said.

Clinton said she's "sorry" there's been so much controversy over her private email server, but declined to apologize for the decision to use it.

"At the end of the day, I am sorry that this has been confusing to people and has raised a lot of questions, but there are answers to all these questions," Clinton said of her email server.

"And I take responsibility and it wasn't the best choice."

The FBI is investigating whether Clinton's use of a private server led to the mishandling of classified material.

"Certainly, it doesn't make me feel good," Clinton said when asked about those who find her dishonest.

"But I am very confident that by the time this campaign has run its course, people will know that what I have been saying is accurate."

Clinton's attack on Trump came as a new Gallup poll found that her favourability with the American public has sunk to one of its lowest levels in more than 20 years.

Forty-one percent of Americans have a favorable view of the Democratic candidate, while 51 percent have an unfavourable view.

On the other hand, Trump's favourable rating among Republicans moved from a 56 percent favourable, 36 percent unfavourable mid-July to a 63 percent favourable, 31 percent unfavourable. But all of this gain over time has occurred among Republican men.