WASHINGTON (AFP) - Hillary Clinton won't make her intentions known about a possible White House before year's end, she said in an interview broadcast Sunday.

"I will be on the way to making a decision by the end of the year," she said in a taped interview with ABC television. "Certainly not before then."

Mrs Clinton's remark came as she embarks on a sweeping book tour for her latest memoir "Hard Choices".

"I just want to kind of get through this year, travel around the country, sign books, help in the midterm elections in the fall, and then take a deep breath and kind of go through my pluses and minuses about what I will - and will not - be thinking about as I make the decision," she said.

Her non-committal remarks notwithstanding, many see Mrs Clinton's book tour launch this week as an unofficial start to her expected presidential run.

Her book, scheduled for publication on June 10, is widely seen as a chance for her to re-craft and fine-tune her image ahead of a 2016 campaign.

Mrs Clinton, 66, who lost to President Barack Obama in their 2008 battle for the Democratic presidential nomination, is mulling a second White House run.

As has been her style, Mrs Clinton spoke opaquely about her political plans, careful not to rule out, or rule in, a future presidential bid.

Meanwhile, a poll released Sunday morning showed she has commanding support among Democrats, making her the prohibitive early favorite to lock up her party's nomination.

The new ABC News-Washington Post poll found that 69 per cent of Democrats and Democratic-leaning independents support her for the party's nomination.

Clinton also fared well among the broader US public, with 67 per cent of Americans viewing her as a strong leader, 60 per cent saying she's honest and trustworthy, and 59 per cent saying she has new ideas for the country's future.

The poll also found that 59 per cent of Americans approve of Clinton's overall job performance as secretary of state.

That number fell to 37 per cent however when respondents were specifically asked about Mrs Clinton's handling of the attack in Benghazi, Libya where a US ambassador and three other Americans were killed.

Mrs Clinton addressed the Benghazi controversy in her book, writing that she refuses to "exploit this tragedy over and over as a political tool" nor would she "minimize the sacrifice of those who served our country," according to excerpts released before publication.